Tolong bantu nomor 9

(x,y) = (2,1)

ax+by = 1

cx+dy = 2

2a+b = 1 —> 2a+b-1 = 0

2c+d = 2 —> 2c+d-2 = 0

2a+b-1= 2c+d-2

2a+b = 2c+d-3