SOLUTION: What is the value of y if (3, y) is a solution to the equation 5x - 3y = 18?

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Question 701643: What is the value of y if (3, y) is a solution to the equation 5x - 3y = 18?
Found 2 solutions by mouk, josgarithmetic:
Answer by mouk(232) About Me  (Show Source):
You can put this solution on YOUR website!
(3, y) are the coordinates of a point satisfying the equation
So when +x=3+ we have
+5x+-+3y+=+18+
+%285%29%283%29+-+3y+=+18+
+15+-+3y+=+18+
+15+-+18+=+3y+
+3y+=+-3++
+y+=+-1++

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
If point, (3, y) is a point on the line with the given equation, then the ordered pair must satisfy the equation. Plug in the numbers from the ordered pair.

x=3, y=y (still unknown).
5x-3y=18
5*3-3*y=18
15-3*y=18 [substitute the values]
15-15-3y=18-15 [add -15 to both sides]
0-3y=3
3y=-3
y=-1. Done.


Check:
5*3-3*(-1)=18?
15+3=18?
18=18, Yes. Done. Checks.