If twice a number added to 3 is divided by a number plus 3, the result is seven fourths, what's the number?

If twice a number added to 3 is divided by a number plus 3, the result is seven fourths, what's the number

Sally can paint a room in 8 hrs while it takes steve 7 hrs to paint the same room. How long would it take them to paint the same room if they worked together?