This will be an obtuse angled triangle because one angle is greater than 90 degrees.
First, there are 26 distinct alphabets and 10 distinct digit numbers.
Then, the first digit of ID has 26 possibilities.
For the rest of 2 digits, the total cases are 10*10 = 100 possibilities.
However, there are 10 cases are repeated when two digits are the same. so you have to subtract it by 10
So answer will be 26 * (100-10) = 23400
First we have - 6 < - 7 - 4x
Then we need to isolate the x of the inequality 4x < - 7 + 6
4x < - 1
x < - 1/4
The values less than - 1/4 are solutions for x
Btw if you need a tutor let me know:)