Answer:
x = 5, y = 15
Step-by-step explanation:
Use substitution to solve the system of equations.
We'll replace y in x + y = 20 with 3x, since y = 3x.
x + 3x = 20
Combine like terms
4x = 20
Divide by 4 on both sides
x = 5
Now to solve for y (don't forget!)
We'll plug x = 5 back into one of the original equations
y = 3(5) = 15
Check first equation:
15 = 3(5)
15 = 15
Check second equation:
5 + 15 = 20
20 = 20
