Ue can wash a car in 1 hour. steve can wash a car twice as fast as sue. how long will it take them to wash a car if they work together, but sue starts 30 minutes before steve?

The rate of Sue is 1 car per hour: 1 (c/h)

then the rate of Steve is 2 (c/h) , because Steve works faster, he can wash twice the number of cars, for the same amount of time.

Thus If Steve and Sue work together, they can wash 1 + 2 = 3 
(cars per hour).

That is, the rate of Steve and Sue working together, is 3 (c/h).
 
In the first 30 minutes, Sue washes half of the car.

The remaining half will be washed at a rate of 3 (c/h)

The main formula is Work = Time * Rate

where Work is washing (1/2)c, and rate is 3(c/h)

Time=Work/Rate = 

1/ 6 h =(1/6)*60 min = 10 min

10 min

29. because you will divide each number of months by 12 to find the number of years. which would mean, 5, 12.5, 16, 45, 50, 72.5. which is crazy. anyhow, i think you find the median in the middle. and yea hope your test goes good