Which expression is equivalent to 18 - 20
O 18+(-20)
18 - (-20)
-18 + 20
- 18 - 20

a. 18 + (-20)

explanation: adding a negative is the same as subtracting a positive

answer: 0+0=0

step-by-step explanation:

that is the only answer that can make 0

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.