Question

Solve the system of equations using elimination.15q – 4r = 625q + 8r = 86A.q = –7, r = –6B.q = 6, r = 7C.q = –7, r = –7

Answer 1

To solve the system we multiply the first equation by 2, then we get:

`\begin{gathered} 30q-8r=124 \\ 5q+8t=86 \end{gathered}`

Now we add the equations:

`\begin{gathered} 35q=210 \\ q=(210)/(35) \\ q=6 \end{gathered}`

Once we know the value of q we plug it in the first equation and solve for r:

`\begin{gathered} 15(6)-4r=62 \\ 90-4r=62 \\ 28=4r \\ r=(28)/(4) \\ r=7 \end{gathered}`

Then q=6 and r=7 and the answer is B.