Question 28471
Walk through it in words
rate working together = faster maid's rate alone + slower maid's rate alone
let x = the faster maids time
let 3x = the slower maids time
(1 house / 3 hours) = (1 house / x) + (1 house / 3x)
1/3 = 1/x + 1/(3x)
multioly both sides by 3x
x = 3 + 1 = 4
so it takes the faster maid 4 hours working alone
check
1/3 = 1/4 + 1/12
lcd is 12
4/12 = 3/12 + 1/12
checks