Answer:
first box is 3. second box is 9. third box is 3
Step-by-step explanation:
x+3y=9
you need to substitute
so
0+3(3)=9
9+3(0)=9
3+3(2)=9
y = 3; x = 6; x = 3
x + 3y = 9
(a) x = 0
0 + 3y = 9
3y = 9
y = 3
(b) y = 0
x + 3(0) = 9
x + 0 = 9
x = 9
(c) y = 2
x + 3(2) = 9
x + 6 = 9
x = 3
