Answer:
2 1/2 hours
Explanation:
multiply their rate by the number of hours
4*2=8
2*2=4
We want them to both equal 15 when added together
8+4≠15
So it's not 2 hours
So now our next answer choice is 2 1/2 hours
Ok that's easy, we can still use what we did from the last answer choice (2 hours)
Since it says 1/2 that means we can multiply the rate by 0.5 or divide it by 2
4/2=2
2/2=1
2+1=3
Now we add that to 8+4
8+4=12
2+1=3
12+3 = 15
Now that we've gotten 15 we know the rest of the answers are incorrect.