Two numbers have an average of 18, and a difference of 10. Form two equations and solve them to find these two numbers.

x = 23 and y = 13

Explanation:

let x and y be the two number.

Where:

(x + y)/2 = 18 => x + y = 18 x 2 = 36

and:

x - y = 10

Thus we get:

x + y = 36 (1)
x - y = 10 (2)

Add (1) and (2):
x + y + x - y = 36 + 10
2x = 46
x = 23

If x = 23

then x - y = 10
23 - y = 10
-y = -13
y = 13

Uneed to add them up 27+18+23=68