Question

for what value k,x=2 and y=-1 is a solution of x+3y-k=0

Answer 1

x=2
y=-1
x+3y-k=0
2+3×-1=k
-1=k

Answer 2

if x = 2 and y = -1
then ,
x+3y-k = 0
2+3×-1 -k = 0
k = -1