Question 893408
 Marukh can wash the car in 10 minutes. Steven can wash the car in 60 minutes.
 If Marukh and Steven work together, how long will it take them to wash the car?
;
let t = time in minutes for them both to wash the car
let the completed job = 1; (a clean car)
:
Each will do a fraction of the job, the two fractions add up to 1
{{{t/10}}} + {{{t/60}}} = 1
multiply thru by 60, cancel the denominators and you have:
6t + t = 60
7t = 60
t = 60/7
t = 8.57 minutes working together
:
:
Check this with your calc:
 {{{8.57/10}}} + {{{8.57/60}}} =