The answer is D= 77, 77-37=40
Explanation
to solve this we need to translate into math terms, so
Step 1
a) let d represents the number of dimes
let n represents the number of nickles
so
re write the expressions

The number of nickels is three more than seven times the number of dimes in other words you have to add 7 to seven times the number of dimes to obtain the number of nickles
hence

therefore , the expression for the number of nickles is

I hope this helps you
If you do 1040-400 you get 640
then you need to divide that by 4 to get 160 leaving you with the width, to get the length you have to add 200 to the width meaning the length is 360
length = 360
width = 160