SOLUTION: 12x + 7y = 19 and 4x - y = 3 then what is the value of 8x + 8y?

Algebra ->  Test -> SOLUTION: 12x + 7y = 19 and 4x - y = 3 then what is the value of 8x + 8y?      Log On


   

Question 441827: 12x + 7y = 19 and 4x - y = 3 then what is the value of 8x + 8y?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

12x+%2B+7y+=+19 and
4x+-+y+=+3...solve the system
---------------------------------
4x+-+y+=+3......solve for y
4x+-+3+=+y......substitute in 12x+%2B+7y+=+19 and solve for x

12x+%2B+7%284x+-+3%29=+19
12x+%2B+28x+-+21=+19
40x+=+19%2B21
40x+=+40
x+=1....now find y
y=4x+-+3+
y=4%2A1+-+3+
y=1+
then the value of 8x+%2B+8y=8%2A1%2B8%2A1=8%2B8=16