8 times the sum of 5 times a number and 9

[math_celebrity]

8 times the sum of 5 times a number and 9

Take this algebraic expression in parts:

The phrase a number means an arbitrary variable, let's call it x.

5 times a number means:
5x

The sum of this and 9 means we add 9 to 5x:
5x + 9

Now we multiply 8 times this sum:
8(5x + 9)