Can someone help me find the y-intercept for two points?

Question

 

My two points are (150,0) and (90,60)
So the slope is -1/1
But I forgot how to find the y-intercept!
If anyone can answer this, thanks a lot!~ C:

 

Answer 1

Slope intercept form line equation is y = mx + b. m is slope and b is y-intercept.

Slope is -1, the line equation is y = -x + b
replace (x, y) = (150, 0) to find the y-intercept
0 = -150 + b
add 150 to each side
150 = b
y-intercept = 150