This is a bit of a weird one, so bear with me.
Tammy cleans 1/2 the area in an hour
Melissa cleans 1/3 the area in an hour.
Together, in one hour, they'd clean 1/2 + 1/3 of the area.
Get a common denominator, 3/6 + 2/6 of the area = 5/6 of the area.
So that's their combined rate. 5/6 of the area per hour.
We want to know how long it takes them to clean the whole area (=1). So (5/6)* X = 1. Divide by 5/6 on both sides.
1 divided by 5/6 is 1 times 6/5.
X = 6/5 of an hour. (about 45% of teachers will want this answer)
Some teachers will want one-and-one-fifth hours. (about another 40% want this one)
Other teachers will want one hour and twelve minutes. (8-10% of teachers will love this answer)
Still other teachers will prefer 72 minutes. (The remaining 5-7% of teachers hold out for this one.)
Any of those four answers could show up on a test, including the ACT.
