Question 947130
Rate x Time = Output 
Let's choose the output to be 100%.
{{{R[m]*4=100}}}
1.{{{R[m]=25}}}
.
.

{{{(R[n]+R[p])*3=100}}}
2.{{{R[n]+R[p]=100/3}}}
.
.

{{{(R[m]+R[p])*2=100}}}
3.{{{R[m]+R[p]=50}}}
Substitute eq. 1 into eq. 3,
{{{25+R[p]=50}}}
{{{R[p]=25}}}
Now substitute this into eq. 2,
{{{R[n]+25=100/3}}}
{{{R[n]=100/3-75/3}}}
{{{R[n]=25/3}}}
So then,
{{{R[n]*t[n]=100}}}
{{{(25/3)*t[n]=100}}}
{{{t[n]=12}}}{{{hrs}}}