Question 986460

Peter can do a whole job in half the time it takes Henry to do it. Together they can finish the job in 10 days. How many days will it take Peter to do the job alone?
<pre>Let time Peter takes be P
Then Henry can do job in 2P days
Peter can do {{{1/P}}} of job in 1 day, and Henry can do {{{1/(2P)}}} of job in 1 day
Together they can do: {{{1/P + 1/(2P) = 1/10}}}
10 + 5 = P -------- Multiplying by LCD, 10P 
P, or time Peter takes = {{{highlight_green(15)}}} days