A machine, working at a constant rate, manufactures 18 pens in 30 minutes. How many pens does it make in 1 hr 45 min?	Choose the most appropriate option:
A) 63 B) 65 C) 62 D) 60 E) 45
Change 1 hr 45 min to 105 min. For this, we need to set up a simple proportion of pens per time   18/30= S/105   The absolutely worst thing you could do at this point in the problem is to cross-multiply. That would be a supremely unstrategic move. Instead, cancel before you multiply. For what we can see this post. We can cancel 18/30 as 6/10   6/10= S/105   we can cross-multiply.   10*S = 6*105= 
<gadget id="calculator">6*105</gadget>
<output>630</output>
630   If we divide both sides by 10,   S= 63   The machine would be 63 pens in 1 hr 45 min.   63nswer: 63
<result>A</result>
A machine, working at a constant rate, manufactures 18 pens in 30 minutes. How many pens does it make in 1 hr 45 min?