Question 959846
Rate x Time = Output
Let the output of 100 be completing the job.
{{{R*t=100}}}
So the rate for the painter is,
{{{R*10=100}}}
{{{R=10}}}
The assistant's rate is,
{{{A*15=100}}}
{{{A=100/15}}}
{{{A=20/3}}}
So then together,
{{{(10+20/3)*t=100}}}
{{{30/3+20/3)*t=100}}}
{{{(50/3)*t=100}}}
{{{t=100(3/50)}}}
{{{t=300/50}}}
{{{t=6}}}{{{hrs}}}