Question

How many integers are between 99 and 201 are divisible by 2 or 5

Answer 1

first no is 100
and last no. is 200
1. a=100,d=2,l=200
find n1 by l=a+(n1-1)d,find n1
2.
a=100,d=5,l=200
find n2 by
l=a+(n2-2)d,
3. L.C.M of 2&5 is 10
a=100,d=10,l=200
find n3 by
l=a+(n3-1) d
Required no.is=n1+n2-n3

Answer 2

i solve for n1
200=100+(n1-1)*2
200-100=(n1-1)*2
100/2=n1-1
50+1=n1
n1=51
similarly you can solve for n2 and n3.