Question 847757
 a small air conditioner will cool a room 2 degrees in 15 min.
 a larger air conditioner will cool the room 2 degrees in 10 min.
 how long would it take to cool the room 2 degrees with both air conditioners running?
:
let t = time required for both a/c units to lower the tem;
let the completed job = 1; lowering the temp 2 degrees
:
A shared work equation
{{{t/15}}} + {{{t/10}}} = 1
mulitply by 30 to clear the denominators, results
2t + 3t = 30
5t = 30
t = 30/5
t = 6 min when both work together