Question

When Mary was born, she weight 8 pounds. When she was 10, she weighed 10 times as much. Write and solve an equation to find the difference between Mary's weight when she was 10 and when she was born.

Answer 1

Δw =
`W_(b)` * 10 -
`W_(b)` = 72 pounds

Explanation:

Using the names

`W_(b)` : weight when born

`W_(10)` :weight when she was then

Δw: weight difference

the equation would be

Δw =
`W_(10)` -
`W_(b)`

since

`W_(10)` =
`W_(b)` * 10

we can replace and we have that

Δw =
`W_(b)` * 10 -
`W_(b)`

and since

`W_(b)` = 8

Δw = 8 * 10 - 8 = 72