How many positive integers less than 160 are there such that they are multiples of 13 or multiples of 12 but not both?	Choose the most appropriate option:
A) 18  B) 19  C) 20  D) 23  E) 25
for 13: 13...160=13*12   for 12: 12...156=12*13   but there is one integer 13*12. so   N=(12-1)+(13-1)= 
<gadget id="calculator">(12-1)+(13-1)</gadget>
<output>23</output>
23   23
<result>D</result>
How many positive integers less than 160 are there such that they are multiples of 13 or multiples of 12 but not both?