SOLUTION: Solve. Jeff takes 5 hours longer to build a fence than it takes Bill. When they work together, it takes them 6 hours. How long would it take Bill to do the job alone?

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: Solve. Jeff takes 5 hours longer to build a fence than it takes Bill. When they work together, it takes them 6 hours. How long would it take Bill to do the job alone?      Log On


   

Question 143821: Solve.
Jeff takes 5 hours longer to build a fence than it takes Bill. When they work together, it takes them 6 hours. How long would it take Bill to do the job alone?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
THE FORMULA FOR THIS PROBLEM IS THE PRODUCT OF THEIR INDIVIDUAL HOURS DIVIDED BY THE SUM OF THEIR HOURS:
X(X+5)/(X+X+5)=6
X^2+5X/(2X+5)=6
X^2+5X=6(2X+5)
X^2+5X=12X+30
X^2+5X-12X-30=0
X^2-7X-30=0
(X-10)(X+3)=0
X-10=0
X=10 HOURS IS THE ANSWER FOR BILL'S TIME TO BUILD THE FENCE.
10+5=15 HOURS FOR JEFF TO BUILD THE FENCE.
PROOF
10*15/(10+15)=6
150/25=6
6=6