9 men and 12 boys finish a job in 12 days, 12 men and 12 boys finish it in 10 days. 10 men and 10 boys shall finish it in how many days?	Choose one.
A) 18	B) 17	C) 12	D) 19	E) 12
9M + 12B ----- 12 days   12M + 12B ------- 10 days   10M + 10B -------?   108M + 144B = 120M +120B   24B = 12M =&gt; 1M = 2B   18B + 12B = 30B ---- 12 days   20B + 10B  18  + 12= 
<gadget id="calculator"> 18  + 12</gadget>
<output>30</output>
30B ---- 12 days   20B + 10B = 30B -----?   20  + 10= 
<gadget id="calculator">  20  + 10</gadget>
<output>30</output>
30B -----?=&gt; 12 days   Answer: 12
<result>C</result>
9 men and 12 boys finish a job in 12 days, 12 men and 12 boys finish it in 10 days. 10 men and 10 boys shall finish it in how many days?