Answer:
4x-3y=21.
Explanation:
1) the common view of slope-interception form is y=slope*x+interception;
2) if according to the condition the slope=4/3, then the required equation is

3) in order to calculate the interception it is enough to substitute the given coordinates into this equation:

4) the slope interception form of the required equation is:

5) if to re-write the equation in slope-interception form into the required, then (A=4; B=-3; C=21):
4x-3y=21.