Question

p+2q-3=0
7p-q-5=0

Answer 1

multiple second equation by 2 and add both equations
15p = 13

Answer 2

p+2q-3=0
p+2q=3-(1)
7p-q-5=0
7p-q=5-(2)
Multiply (2) by 2
That is
(2)*2=>14p-2q=10-(3)
Nw add (1) and (3)
(1)+(3)=>p+2q+14p-2q=3+10
15p=13
solve for p.
Then substitute the value of p in
q=7p-5
to find q.