Help ...Lesson Three :

The first crew works at a rate of 1/18 of a complete job per

hour. The second crew works at a rate of 1/12 of a complete

job per hour. If "x" is the time required by the two crews together,

then the first will do 1/18 of "x" and the second can do 1/12 of "x".

Therefore,  the equation needed to solve this problem is :

x/18 + x/12 = 1 (completed job)

x = 7.2 hours

[RETURN]