The sum of two numbers is 42 and the difference is 20

Answer 1

Let the two numbers be x and y.

x + y = 42

x - y =20.

Adding the two equations together...

x+y + x-y = 42+20

2x = 62

x = 31.

Substituting in the first equation.

31 + y = 42.

y = 11.

The two numbers are 31 and 11.

To double-check the answer. 31 + 11 = 42, and 31-11 = 20.

Answer 2

I used different options such as 10 and 32 (wrong) then 11 and 31 (right) after trying 12 and 30 (wrong), and 9 and 33 (wrong).

Answer 3

x + y = 42

AND

abs| x - y | = 20

This would work:

X = 11

Y = 31

How I got there: Start extreme: can it be 1 and 41? No, they're too far apart... Get less extreme: 20 and 22? No, they're too close.