If Tyler and Maria can paint their kitchen in 5 hours and Maria can paint it in 9 hours by herself how long would it take Tyler to do it alone?
Tylers rate = 1/x kitchens/hr
Mary's rate = 1/9 kitchens /hr
combined rate = 1/5
but combined rate = 1/x + 1/9
= (9+x)/(9x) = 1/5
9x = 45+5x
4x=45
x = 45/4 = 11.25 hrs
Alone would take him 11.25 hrs