Question 805262
Person A can paint the neighbors house 2 times as fast as person B.
 The year A and B worked together, it took them 6 days. how long would it take each to paint the house?
Let a = A's time to paint the house
then
2a = B's time to do it
:
Let the completed job = 1; (a painted house):
Each will do a fraction of the job, the two fractions add up to one.
{{{6/a}}} + {{{6/(2a)}}} = 1
multiply by 2a, cancel the denominators
2(6) + 6 = 2a
18 = 2a
a = 9 days for A working alone
then
2(9) = 18 days for B to do it.