The sum of two numbers is 57 and the difference is 13 what are the numbers

Let the numbers be x and y

x  + y  =  57          (i)
x  -  y  =  13          (ii)

Add equations (i) and (ii)  to eliminate y

x  + y  + x  -  y   =  57 + 13
x + x  + y - y =   57 +13
2x  =     70
x  =  70/2 = 35

From (i)  x  + y  =  57
              35 + y = 57
                      y = 57 - 35
                      y  =   22

The numbers are 35 and 22.

Guess and Check!
N1=Number 1
N2=Number 2

n1 + n2 = 57

n1 - n2 = 13

2n2 = 70

n2 = 35

n1 = 57 - 35 = 22

 22 and 35=number