Drag equations to each row to show why the equation of a straight line is y = mx + b, where m is the slope and b is the y-intercept.

y-b/x = m/1 Triangle 1 is similar to triangle 2

y-b=mx Multiply both sides by x.

y=mx+b Add b to both sides.

m is the slope because it is affected by the value of x. They are multiplied together and therefore are affected by one another.

The b is the intercept because even when the x value is 0, the value of the y-intercept exists.