A 2 digit number is such that thrice the sum of its digits is less than the value of the number by 8. When the digits are reversed the number increases by 9.
Find the number.

23

Step-by-step explanation:

Let "ab" represent the digits of the number.

"thrice the sum of its digits is less than the value of the number by 8"

The value of the number is 10a+b.

3(a+b) = (10a+b) - 8

3a+3b = 10a+b-8

7a-2b = 8

"When the digits are reversed the number increases by 9"

Value of "ba" = 10b+a

(10b+a) - (10a+b) = 9

9b-9a = 9

b-a = 1

b = a+1

7a-2(a+1) = 8

5a -2 = 8

a = 2

b = a+1 = 3

"ab" = 23

the expected value of the random variable : 0, 1 and 2

step-by-step explanation:

answer: a.

step-by-step explanation: the answer is a. because, you need to converge the fractions to find a solution.