90:18
divide using 3 on both sides
90:18
30:6
10:2
now lets use 2
10:2
5:1
5:1 is the equal ratio to 90:18
The slope-intercept form of a linear equation is given by:

Where m is the slope and b is the y-intercept.
If the slope is -17/12, we have m = -17/12.
Now, to find the value of b, let's use the ordered pair (12, -8) in the equation:

So our equation is:
Multiply the entire top equation by -3 then proceed to cancel the nines then slove