Two musicians, Maria and Perry, work at independent constant rates to tune a warehouse full of instruments. If both musicians start at the same time and work at their normal rates, they will complete the job in 120 minutes. However, if Perry were to work at twice Maria’s rate, they would take only 20 minutes. How long would it take Perry, working alone at his normal rate, to tune the warehouse full of instruments?	Choose the correct answer:
A) 1 hr 20 min	B) 1 hr 45 min	C) 2 hr	D) 2 hr 20 min	E) 1 hr
Sol:   Lets Perry Rate be P and Rate of Maria be M   (rate)*(time)= Work or rate = work/time   first equation=&gt; P+M = 1/120   converting it to hrs P+M= 1/(60/120)= 
<gadget id="calculator">1/(60/120)</gadget>
<output>2</output>
&gt; 2   second equation=&gt; M+2M =&gt;1/20   converting it to hrs 3M=1/(20/60) =&gt;1/(1/3)= 
<gadget id="calculator">1/(1/3)</gadget>
<output>3</output>
&gt;3   therefore M= 1 and P=1   Rate of Perry = 1   time= work/rate (work = 1 job)   Time= 1 hrs   Answer : 1 hr
<result>E</result>
Two musicians, Maria and Perry, work at independent constant rates to tune a warehouse full of instruments. If both musicians start at the same time and work at their normal rates, they will complete the job in 120 minutes. However, if Perry were to work at twice Maria’s rate, they would take only 20 minutes. How long would it take Perry, working alone at his normal rate, to tune the warehouse full of instruments?