system of equations (1,1)
put value of these x and y in equations
(x , y) = ( 1,1)
so this solution not satisfied equation 1
11( 1) + 3 (1) = 18
so 11 + 3 = 18
15 = 18 ( Left side not equal to right side )
(1,1) is not solution for 11x+ 3y=18
2. 4x+y = 5
put values (1,1)
4(1) + (1) = 5
5 = 5 { left side = right side )
so (1,1) is solution for 4x +y=5