If 28a+30b+31c=520.
then a+b+c=?.a,b,c are natural numbers  Select the correct option:
A) 18
B) 20
C) 17
D) 42
E) 16
have a look on your calender   since,we all knw a year consist of 365 days   february is d only month which has 28 days   4 months in a year has 30 days   and,rest 7 months has 31 days..   so,following d given eq. we can write 28*1 + 30*4 + 31*12..   hence values of a,b and c are 1, 4 and 12 respectively..   a+b+c=17   ANSWER:17
<result>C</result>
If 28a+30b+31c=520.
then a+b+c=?.a,b,c are natural numbers