Circular gears P and Q start rotating at the same time at constant speeds. Gear P makes 10 revolutions per minute and Gear Q makes 40 revolutions per minute. How many seconds after the gears start rotating will gear Q have made exactly 45 more revolutions than gear P?  Options:
A) 45
B) 80
C) 90
D) 100
E) 120
Gear Q makes 30 more revolutions each 60 seconds.   The time to make 45 = 30*1.5 more revolutions is 60*1.5= 
<gadget id="calculator">60*1.5</gadget>
<output>90</output>
90 seconds.   The answer is 90.
<result>C</result>
Circular gears P and Q start rotating at the same time at constant speeds. Gear P makes 10 revolutions per minute and Gear Q makes 40 revolutions per minute. How many seconds after the gears start rotating will gear Q have made exactly 45 more revolutions than gear P?