Answer: y = 3x-15
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Explanation:
The slope of the blue line is m = 3 since y = 3x is really y = 3x+0. Compare this to y = mx+b.
Parallel lines have equal slopes. The red line will also have a slope of m = 3.
Plug in m = 3, x = 4 and y = -3 into y = mx+b and solve for b. The x and y values come from the point (4,-3)
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y = mx+b
-3 = 3(4)+b
-3 = 12+b
-3-12 = b
-15 = b
b = -15
Since m = 3 and b = -15, this means y = mx+b turns into y = 3x-15
