Using the substitution p=1/x, q=1/y. Solve the simultaneous equation 1x-5/y =7 and 1/x+1/y =3

Answer 1

Not 1/x-5/y =7 ?
If so
p - 5 q = 7
p + 1 q = 3
------------------- subtract
0 - 6 q = 4
q = -2/3
then p -2/3 = 3
p = 11/3
x = 3/11
y = -3/2

Answer 2

Another method