Two-digit numbers range from 10 to 99.
The first two-digit number divisible by 3:
10 ÷ 3 is not a whole number
11 ÷ 3 is not a whole number
12 ÷ 3 = 4
The first two-digit number divisible by 3 is 12.
The last two-digit number divisible by 3:
99 ÷ 3 = 33
The last two-digit number divisible by 3 is 99.
The two-digit numbers divisible by 3 form the sequence: 12, 15, 18, 21, 24, ... 96, 99
Each number is 3 more than the previous one (common difference = 3).
For a sequence with constant difference:
Number of terms =Common differenceLast−First+1
n=399−12+1
n=387+1
n=29+1
n=30
Therefore, there are 30 two-digit numbers divisible by 3.
The answer is Option 1: 30