Line A passes through the points (-1, 4) and (4, 9). Line B passes through the points (4, -4) and (-3, 24). Find the point where line A intersects line B

Acertain drug is made from only two ingredients: compound a and compound b. there are 3 millimeters of compound a used for every 4 millimeters of compound b. if a chemist wants to make 693 milliliters of the drug, how many milliliters of compound a are needed?