What sum of 2 numbers is 10 and a difference of 20?

Answer 1

Sum = addition

Difference = subtraction

Say your first number is x and your second number is y. So:

x+y = 10 and x-y = 20

Solve for one variable for one of the above equations and substitute that variable into the other equation:

x = 10-y

(10-y)-y = 20

10-2y = 20

Get y by itself:

-2y = 20-10

-2y = 10

Solve for y:

-2y/-2 = 10/-2

y = -5

To solve for x:

x = 10-y

x = 10-(-5)

x = 10+5

x = 15

Therefore, the two numbers you are looking for are -5 and 15.