Question

It takes 10 minutes to bake a batch of cookies. You need to bake 7 batches of cookies. How long will it take to bake all the cookies?

Answer 1

You know 1 batch of cookies = 10 minutes

Now, 7 batch of cookies = ?
To do this just do 7×10=70.
So the answer is 70 minutes = 7 batch of cookies.

You can also set up a proportion.

10 x
__ = ____
1 7

Cross multiply and 7×10=70 and 10x. So now its like this.
70= 10x
÷10 ÷10
_________
7=x

So the answer is 7.