find an equation of the line containing the given pair of points.
(0,0) and (4,9)
is the answer (9/4)
The slope is 9/4. Now, you have more.
y=mx+b
you found m, the slope
y=9/4 m + b
Now to find b put in one of the points. 0,0 is an easy one.
0=9/4 *0 + b
so in this case, b is zero (It usually IS NOT).
so...
y=9/4 x + 0 or
y=9/4 x is the equation for the line.