Representing 2-step word problems | 3rd grade math (Illustrative Math-aligned) | Khan Academy

- [Instructor] We're told
a bakery sold 144 cookies,

308 cupcakes,

and 180 loaves of bread over the weekend.

How many items did the
bakery sell all together?

So what we need to do is
pick the strip diagram

that would actually help
us answer this question.

So pause this video and think about

which of these three you would pick

that would actually help
us answer the question of

how many items did the
bakery sell all together?

All right, now let's work
through this together.

So they're giving us

the different items.

So we have cookies,

we have

cupcakes.

Lemme do that in a different color.

I'll do this in blue.

We have the cupcakes and then
we have the loaves of bread,

and then we have the loaves of bread.

Now if we want 'em all together,
we want to add them up,

so I wanna see a strip diagram
that adds these together.

So let's see.

This first one, it looks
like it's adding 144 and 308,

the cookies and the cupcakes,

but then it has the
loaves of bread over here.

So the loaves of bread plus something else

is going to be the same as
the cookies and the cupcakes.

That doesn't make sense.

Now, choice B here, it looks like

it's got the cookies here, 144,

it's got the cupcakes, 308,
it has 180 loaves of bread.

They're using different colors than I used

and we have one strip after the other

and they're all being added together

for this total amount right over here.

So that makes sense.

You would add these together
to get the total amount.

So I like this choice.

Now let's just make sure
this one doesn't make sense.

This one is saying if I have 180 and 144

and something else, what
is the something else

to get to 308? We're not
trying to get to 308.

308 is the number of cupcakes.

We're trying to get the total.

So once again, we want
to go with choice B.

Let's do another example here.

So

now

we

are told

that Diego has $700 in his bank account.

He spent $186 shopping.

The next day he deposited $45,

that means putting money
back into the bank account.

How much money is in
Diego's bank account now?

So which of these number
lines actually show that

or would be helpful for figuring out

how much is in his bank account now?

So let's look at these choices.

This first one, actually,
all of them start with 700.

They go from zero to 700, we
see that in all of the choices.

Now in this first one,
we go from zero to 700

and then it looks like we
are then taking back 186,

which actually makes sense.

So lemme color code it.

So the $700 in the bank account,

it looks like they all show that.

It goes from zero to 700 right over there.

Spent $186,

so if you're spending it,

that would go out of the bank account,

so that should decrease the number.

So this purple line,

it looks like we are subtracting 186 here,

looks like we're subtracting 186 here.

This one doesn't make sense.

It looks like we're adding another 186,

so I'm going to rule this one out already.

And then after we subtract 186,

this first choice is then

looks like it's
subtracting another amount.

Let's call that, maybe that's the 45

in green right over here.

Lemme put that in the same color.

So maybe that's the 45.

But if you're depositing $45,

that should increase your bank account,

so you shouldn't go down another 45,

you shouldn't subtract 45,
so I don't like this one.

Choice B looks right.

We have 700, we took out 186 spending it,

and then from that point,
we add back another 45,

so I am liking

choice B.