-9x + 4y = 55. –------------- (1)
-11x + 7y = 82. ---------------(2)
Multiply (1) with 7 and (2) with 4. we get
-63x + 28y = 385 ----------(3)
-44x + 28y = 328 ----------(4)
Subtract (4) from (3). you will get
-19x = 57
=> x = 57/(-19)
=> x = -3
Put value of x in (1)
-9×(-3) + 4y = 55
=> 27 + 4y = 55
=> 4y = 55 - 27
=> 4y = 28
=> y = 28/4 = 7
-11x + 7y = 82. ---------------(2)
Multiply (1) with 7 and (2) with 4. we get
-63x + 28y = 385 ----------(3)
-44x + 28y = 328 ----------(4)
Subtract (4) from (3). you will get
-19x = 57
=> x = 57/(-19)
=> x = -3
Put value of x in (1)
-9×(-3) + 4y = 55
=> 27 + 4y = 55
=> 4y = 55 - 27
=> 4y = 28
=> y = 28/4 = 7