Question

Suppose 3x + 4y = 52 and 5x + y = 30. What is the value of 8x − 2y?

Answer 1

Hi !

We have to resolve an equation system to find x and y


`\begin{cases}3x+4y=52\\5x+y=30\end{cases}\\\\\begin{cases}3x-4y=52\\y=30-5x\end{cases}\\\\\\3x+4*(30-5x)=52\\3x+120-20x=52\\-17x+120=52\\-17x=52-120\\-17x=-68\\\\x=(68)/(17)\\\\\boxed{x=4}\\\\\\y=30-5*4\\y=30-20\\\\\boxed{y=10}}\\\\8x-2y=8*4-2*10\\8x-2y=32-20\\\\\boxed{8x-2y=12}`