Question

Puzzle 
If a + b = 76
a - b = 38
a / b = ????????????

Answer 1

First we need to calculate how much is a and b, from the first and second equations, and then we take care of each other:
a + b = 76
a - b = 38
a / b = ?


`\begin{cases}a+b=76\\a-b=38\end{cases}|+`

`a+a+b-b=76+38`

`2a=114|:2`


`a=57`

`a+b=76`

`57+b=76`

`b=76-57=19`


`(a)/(b)=(57)/(19)=3`

Answer 2

`+\left\{\begin{array}{ccc}a+b=76\\a-b=38\end{array}\right\\-----------\\.\ \ \ \ \ \ \ 2a=114\ \ \ \ \ |:2\\.\ \ \ \ \ \ \ \ \ \ a=57\\\\57+b=76\\b=76-57\\b=19\\\\(a)/(b)=(57)/(19)=\fbox{3}`