In order to find the equation of a line, you would have to use the equation y=mx+b.
First, find the slope:
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There is (1,8) and (2, 16) so plug that in 16-8/2-1 = 8. That's your slope! (Or the m)
Next in order to find b, you have to plug in a point:
y=8x+b
Take (1,8) and plug it in for x and y:
8=8(1)+b
b=0
Your y intercept is 0 (which you can also see on the graph)
So your answer is: y=8x