Question

Solve the simultaneous equation
3p+q=11
p+q=3

Answer 1

q=3-p
3p+(3-p)=11
2p=8
p=4

q=3-4
q=-1

Answer 2

`3p+q=11 \\ p+q=3 \ \ \ |* (-1) \\ \\ 3p+q=11 \\ \underline{-p-q=-3} \\ 3p-p=11-3 \\ 2p=8 \\ p=(8)/(2) \\ p=4 \\ \\ p+q=3 \\ 4+q=3 \\ q=3-4 \\ q=-1 \\ \\ \boxed{(p,q)=(4,-1)}`