Question time pls help me

This polygon has 4 sides
180(4-2) = 180(2) = 360 degree
80+90+2x + 3x = 360
170+5x = 360
5x = 190
x= 38
measure of angle t is 2(38)= 76
the answer is c. trust me
hope this !

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.