2x+5y=10 , -7x-4y=16

Answer 1

Are solving ?

1st times 4 ----> 8x + 20y = 40
2nd times 5 ---> -35x - 20y = 80

add them
-27x = 120
x = -40/9

into the 1st:
-80/9 + 5y = 10
-80 + 45y = 90
45y =170
y = 34/9