A metal company's old machine makes bolts at a constant rate of 100 bolts per hour. The company's new machine makes bolts at a constant rate of 150 bolts per hour. If both machines start at the same time and continue making bolts simultaneously, how many minutes will it take the two machines to make a total of 450 bolts?	Choose the correct choice from the following choices:
A) 36
B) 72
C) 120
D) 144
E) 108
Old Machine   100 bolts in 60 mins   so,   5/3 bolts in 1 min   New Machine   150 bolts in 60 mins   so,   5/2 bolts in 1 min   together,   5/3 + 5/2 =   25/6 bolts in 1 min   so, for 450 bolts   450 * 6 / 25= 
<gadget id="calculator">450 * 6 / 25</gadget>
<output>108</output>
108 mins   Ans 108
<result>E</result>
A metal company's old machine makes bolts at a constant rate of 100 bolts per hour. The company's new machine makes bolts at a constant rate of 150 bolts per hour. If both machines start at the same time and continue making bolts simultaneously, how many minutes will it take the two machines to make a total of 450 bolts?