word problem

[Stephanie Paige Upton]

I can't figure this problem out.

If one guy can paint a house in 3 hours and another guy can paint the house in 5 hours, how long would it take both guys to paint the house if they painted it at the same time?

I called guy 1 (Bob) = x
guy 2 (Joe) = y

x=3, and y=5, then (x) +(x+2) = ? this is where I got stuck.

 

[Stephanie Paige Upton]

ok. so in one hour they paint 8/15 of the house:

1/3 + 1/5 = ?
5/15 + 3/15 = 8/15

but what about the remaining 7/15ths of the house?

 

[Stephanie Paige Upton]

We don't give full solutions; but here's another hint:
you know that 8/15 of house takes 1 hour (or 60 minutes);
next, calculate how long it takes for 7/15 of house.

ugh! so, 8/15 = 60 min
7/15 = ?

8/15 60
____ = _____

7/15 x

which means x=52.5 minutes..... correct?

 

[stapel]

ok. so in one hour they paint 8/15 of the house:

1/3 + 1/5 = ?
5/15 + 3/15 = 8/15

but what about the remaining 7/15ths of the house?

One hour allowed for 8/15 of the house. Then 60 minutes allowed for 8/15 of the house, so (7.5)*8 minutes allowed for 8/15 of the house.

Then how many minutes are required for 1/15 of the house? For 7/15 of the house?