Question 5093
If Sally can paint the house in 4 hours, then the part she can do in 1 hour is {{{1/4}}}.


If John can paint the house in 6 hours, then the part he can do in 1 hour is {{{1/6}}}.

Let x = the number of hours it takes them to paint the house together.

If together they can paint the house in "x" hours, then in 1 hour they can paint {{{1/x}}} of the house.


The equation is "The part Sally can paint in 1 hour + the part that John can paint in 1 hour equals the part they can paint together in 1 hour."

{{{1/4 + 1/6 = 1/x}}}


Multiply both sides of the equation by the least common denominator which is {{{12x}}}.

{{{(12x)*(1/4) + (12x)*(1/6 )= (12x)*(1/x) }}}
{{{3x + 2x = 12}}}
{{{5x = 12}}}
{{{x= 12/5}}} hours or 2.4 hours.


R^2 at SCC