Hello,

there are a lot of different methods to solve this system of simultaneous equations. I'll demonstrate 2 of them:

First rearrange the 2nd equation!

1. multiply the 2nd equation by 4: and add columnwise:

. Plug in this result into any of the 2 equations and solve for e.

2. Solve the 2nd equation for e: e = 2f - 11 and substitute e by this term in the first equation:

Plug in the result for f into the 2nd equation.