Timmy and His Dad
15) Though it takes young Timmy 3 hours to do all the yard work,
his father can do the same in 2 hours. If they both work together,
how long will it take?
1 1 1
---- + ---- = ----
3 2 x
Since it takes Timmy 3 hours to do the yard work, then he
can do 1/3 of it in 1 hour.
Find the lowest common denominator:
L.C.D. = 6x
6x (1) 6x (1) 6x (1)
--- + --- = ---
3 2 x
Working each fraction:
6x/3 = 2x
2x * 1 = 2x
6x/2 = 3x
3x * 1 = 3x
6x/x = 6
6 * 1 = 6
2x + 3x = 6
5x = 6
x = 1.2 hours, or 1 and 1/5 hours, or 1 hour and 12 minutes.
NOTE: To figure out the minutes from a decimal number, simply
multiply it by 60: e.g. 0.2 * 60 = 12