if the '7t' is supposed to be '7y', then the answer is below
(4y+8)-(7y-12)=11
distribute the negative into the second parenthesis
4y+8-7y+12=11
combine like terms
-3y+20=11
subtract the 20 from both sides
-3y=-9
divide by -3 on both sides
y=3
if it is supposed to be '7t', I'm not sure if there's enough information