Question

Solve the equation 6x + 3y = 15 for y. What does y equal if x = 2? If x = 5?

Answer 1

6(2)+3y=15
12+3y=15
-12        -12
3y=3
3y/3  3/3
y=1

6(5)+3y=15
30+3y=15
-30        -30
3y=-15
3y/3   -15/3
y= -5

Answer 2

6x + 3y = 15 (without plugin)
Now add the plugin for 2
6(2) + 3y = 15 (now solve for y)
12 + 3y = 15 (do 6 x 2)
3y = 3 (subtract 12 from each side)
y = 1 (divide each by 3)


Now the plugin for 5
6(5) + 3y = 15 (now solve for y)
30 + 3y = 15 (do 6 x 5)
3y = - 15 (subtract 30 from each side)
y = -5 (divide each side by 3)

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