6x + 3y = 15 , if x = 2 :
6(2) + 3y = 15 Plug 2 into x
12 + 3y = 15
-12 -12 Subtract 12 for both side
3y = 3 Divide 3 for both side
y = 3
6x + 3y = 15 , if x = 5 :
6(5) + 3y = 15 Plug 5 into x
30 + 3y = 15
-30 -30 Subtract 30 for both side
3y = -15
/3 /3 Divide 3 for both side
y = -5
