1. The perimeter is at most 130 cm. 2. The length of the rectangle is 4 times the width. We can let l stand for length and w for width.
The formula for the perimeter of a rectangle is 2l + 2w. We have to change the formula a bit. The length of this rectangle is going to be 4 times the width So, replace 2l with 2(4w).
Then make this equation equal to 130.
2(4w) + 2w = 130 ; Start 8w + 2w = 130 ; Distribute the 2 across the 4w 10w = 130 ; Combine the like terms 8w and 2w w = 13 ; Divide both sides by the coefficient of w. Which is 10
He was wrong, you cannot make 10 coins by adding 32 coins to 28 coins. If you want to obtain 10 coins from 32 coins and 28 coins, you can subtract 28 coins from 32 coins. This can be illustrated as follows: 32-28=10
