Question

{ 1,2.3,..........,210 }

How many numbers in the above set are multiples of 3 but not 9 ?

a. 46
b. 47
c. 48
d. 69
e. 70

please answer and explain

Answer 1

There are obviously 70 multiples of 3 (210/3 = 70)

So, how many multiples of 9 are there?

Figure the difference.

Answer 2

210/9=23.333

so 70-23 =47

answer b ?

Answer 3

Looks good to me.