How many positive integers less than 130 are there such that they are multiples of 13 or multiples of 12 but not both?  Select the correct option.
A) 16 B) 18 C) 20 D) 24 E) 28
for 13: 13...130=13*10   for 12: 12...130 =12*10   but there is one integer 13*12. so   N=(10)+(10)= 
<gadget id="calculator">(10)+(10)</gadget>
<output>20</output>
20   20
<result>C</result>
How many positive integers less than 130 are there such that they are multiples of 13 or multiples of 12 but not both?