Problema Solution
Twin brothers, Andy and Brian, can mow their grandparents lawn in 18 minutes. Brian can mow the lawn by himself in 15 minutes more than it would take Andy. How long would it take each person to mow the lawn alone?
Answer provided by our tutors
Let
x = the number of minutes it takes Andy to mow the lawn alone, x>0
1/x lawn per min is the rate of Andy
x + 15 = the number of minutes it takes Brian to mow the lawn alone
1/(x + 15) lawn per min is the rate of Brian
1/18 lawn per min the together rate
1/x + 1/(x + 15) = 1/18
........
........
x = 30 min
x + 15 = 30 + 15 = 45 min
It takes 30 minutes for Andy to mow the lawn alone.
It takes 45 minutes for Brian to mow the lawn alone.