We have to write the expression for "3 times the sum of twice a number and 8".
Twice a number can be written as 2r, where x is the number.
The sum of twice a number and 8 can be written as 2r+8.
Then, three times this sum is 3(2r+8).
Answer: we can write the expression in mathematical terms as 3(2r+8) [third option]