Answer:
x = 8; y = 15
Explanation:
First choose any one equation and isolate a variable of your choice
I will use the first equation and isolate variable y
9 = 3x - y
Add y to both sides to make it positive
y + 9 = 3x - y + y
Subtract both sides by 9 to isolate the variable y
y + 9 - 9 = 3y - 9
y = 3x - 9
Now that we know what expression is equal to y, we can substitute this value of y into the second equation
6x = 3(3x - 9) + 3
Use distributive property
6x = 9x - 27 + 3
Combine like terms
6x = 9x - 24
Subtract both sides by 9x
6x - 9x = 9x - 9x - 24
-3x = -24
Divide both sides by -3 to isolate the variable x
-3x ÷ -3 = -24 ÷ -3
x = 8
Plug this value of x into either equation
I will use the first equation because it is shorter
9 = 3(8) - y
9 = 24 - y
Add y to both sides to make y positive
y + 9 = 24 - y + y
y + 9 = 24
Subtract 9 from both sides to isolate the variable y
y + 9 - 9 = 24 - 9
y = 15