Question 643992
If Sally can paint a house in {{{4}}} hours, then she can paint {{{1/4 }}}of a house in {{{1}}} hour.

If John can paint a house in {{{6}}} hours, then he can paint {{{1/6}}} of a house in {{{1}}} hour.

Let {{{x}}} be the number of hours it would take them to paint the house.

Working together, they can paint {{{1/x}}} of the house in {{{1}}} hour, so

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

Multiply by LCD, so {{{12(1/4 + 1/6) =12(1/x)}}}

{{{12(1/4) + 12(1/6) =12/x}}}

{{{cross(12)3(1/cross(4)1) + cross(12)2(1/cross(6)1) =12/x}}}

{{{3+2=12/x}}}

{{{5=12/x}}}

{{{5x=12}}}

{{{x=12/5}}}

{{{x=2.4}}} hours. Also, {{{0.4=40}}} % of {{{60}}} minutes is {{{24}}} minutes.

Final answer = {{{2}}} hours and {{{24}}} minutes.