Question 627012
It takes Jake 11 hours to proof read a chapter
 and Mandy 9 hours to proof read a chapter.
 How long would it take them working together?
 (Round you answer to two decimals).
:
Let t = time required when working together
Let the completed job = 1
:
A typical shared work equation
{{{t/11}}} + {{{t/9}}} = 1
multiply by 99,  to clear the denominators
99*{{{t/11}}} + 99*{{{t/9}}} = 99
cancel the denominators
9t + 11t = 99
20t = 99
t = 99/20
t = 4.95 hr together