Question

I know the answers but someone tell me why its that answer! And also a better understanding.

Answer 1

For No. 2 because you will run out of pink material first.
3/4 = .75
How many .75 are there in 2?

.75x2 = 1.5
.75x3 = 2.25

So you would be .25 yards short material for the next costume.

Answer 2

So you will find these answers for 1 you will need to be multiplying the amount of fabric for ONE costume multiplied by EIGHT which is the amount of costumes. (ex. 1 1/2*8)

For number 2 you would divide each amount of fabric by the original fabric.

(ex. 10 divided by 1 1/2)