The sum of the two numbers is 12. The difference of the same two numbers is -4

Answer 1

x + y = 12

x - y = -4

Add the 2 equations to eliminate the y.

2x = 8

You should be able to solve it from here.

Answer 2

We have 2 unknowns, therefore we need 2 equations to solve this.

Let x = the first number

y = the second number

Eq. I: x + y = 12

Eq. II: x- y = -4

We can use either the substitution method or the elimination method to solve for either one of the unknowns. Let's use the elimination method and solve for x by adding the 2 equations together:

x + y = 12 Eq. I

x - y = -4 Eq. II

2x = 8 add the 2 equations

x = 8/2 divide both sides by 2 to isolate x

x = 4 solve for x

By substituting this value for x in either Eq. I or Eq. II we can then solve for y:

x + y = 12 Eq. I

4 + y = 12 substitute 4 for x

y = 12 - 4 subtract 4 from both sides to isolate y

y = 8 solve for y

The answers are x = 4 and y = 8.

Hope this helps!