Question 991688
We have a formula for velocity; it says that v=at, where v is the final velocity, a is the average acceleration and t is the time the body accelerates.

The acceleration is unknown, but you can express it in terms of F and m: F=ma.

If we combine these two formulas, we can say that: vfinal= (F/m)t= (Ft)/m. Now applying this formula to your numbers:
vfinal= (20*24)/6 = 80
vfinal= (20*24)/10= 24

Notes: Your problem is stated in lbs. These formulas are typically in: N for the Force, kg for mass, and meters/second squared (m/s^2) for the acceleration. I don't know if you have to convert or not. If you do: 1lb Force= 4.44822162 newtons; 1lb mass= 0.453592kg