The sum of two numbers is 20, and the difference is 40

-10 and 30

The numbers are 30 and -10.

Step-by-step explanation:

The sum of two numbers is 20 (addition)

x + y = 20

The difference is 40 (subtraction)

x - y = 40

To solve an equation, you can only have one variable. Solve one of these for a variable (it doesn't matter which one).

x - y = 40   Add y to both sides

x = 40 + y

Now you have a new value for x (40 + y), so you can plug it into your other equation.

x + y = 20   Plug in (40 + y) for x

40 + y + y = 20   Combine like terms (y + y)

40 + 2y = 20   Subtract 40 from both sides

2y = -20   Divide both sides by 2

y = -10

Now, plug your y into either equation.

x + y = 20   Plug in -10 for y

x + (-10) = 20   Simplify

x - 10 = 20   Add 10 to both sides

x = 30

Check your work by plugging these numbers into both equations.

x + y = 20   Plug in

30 + (-10) = 20   Simplify

30 - 10 = 20   Simplify

20 = 20

and

x - y = 40   Plug in

30 - (-10) = 40   Simplify

30 + 10 = 40

40 = 40

step-by-step explanation: