m is the slope of the line. (0=horizontal, 1=45 degrees, etc.)

b is the y-intercept (it’s where it crosses the y-axis).

You have to use the information in the problem to determine what m and b are.

For 15, plug in x and y to get two equations containing m and b, then solve for m and b.

For 16, parallel lines have the same slope (m), so use that to find m first, then find b.

I’ll get you started.

15)

0 = m*15 + b

3 = m*5 + b

Solve for m and b.

Then the answer is “y = mx + b” except replace m and b with the actual numbers.

16).

y = -2x + 15, so you know that m=-2.

So, y = -2x + b.

Plug in x=3, y=0:

0 = -2*3 + b.

Solve for b.

Hope this helps!