7x-4y=-8 and y=3/4x-3

7x-4y=-8 ... (i)

y=3/4x-3 ... (ii)

Putting the value of y in eqn (i)

7x-4y=-8

or, 7x-4 (3/4x-3) = -8

or, 7x-3x+12=-8

or, 4x=-8-12

or, x=-20/4

x=-5

again,

putting the value of x in eqn (ii)

y=3/4x-3

y=-5 (3/4) - 3

y=-15/4 - 3

y=-3/4

x=-5

y=-3/4