you can set this up as an equation. We have luke, we will make him variable L
we also have sam, we will make him variable S
There is 1 house so we can refer to the house as 1
so we know that 2 hours of sams work will clean the house
2S=1
and we know that 3 hours of lukes work will clean the house
3L=1
If each of them clean half of the house we could say that
2s=1/2
and
3l=1/2
solve for s and l
s=1
l=1.5
then add s and l together
1 + 1.5 = 2.5 hours