Let the numbers be x and y
Sum of the number: x + y = 54 -----------------------(1)
x - y = 20-------------------------(2)
solving equation simultaneously using elimination method.
x + y = 54 -----------------------(1)
x - y = 20-------------------------(2)
subtracting equation (2) from (1)
x + y = 54 -----------------------(1)
-(x - y = 20-------------------------(2)
(x - x) + (y - -y) = 54 - 20
0 + (y + y) = 34
2y = 34
y = 34/2 = 17
y = 17
put the value of y into equation (1) so as to be able to get x
x + 17 = 54
x = 54 - 17
x = 37
Therefore the answer is x 37 and 17