Answer:
m=20, b=0
equation: y=2x
proportional? YES
Explanation:
"m" means the slope of the line. To find the slope, we have to use the equation (y1-y2)/(x1-x2). Find two random coordinates plotted on the line, and plug the x and y into that equation. We can do (40-20)/(3-2).
(40-20)/(3-2)
(20)/(1) = 20
m = 20
"b" means the y-intercept, and to find that we look for where the line goes through at the y-axis. We can see that the line goes through the y-axis at (0,0) - so "b" is 0.
To create an equation, we use the equation y=mx+b. We know the "m" and "b" now, so easily we can put them into the equation and it becomes: y=2x+0
Which is also just y=2x (because 0 is nothing)
It's proportional because the y-intercept is 0.
Hope this helped :)