so first you take the words and put them into an equation. "a number" that never gets directly told to you will always be a variable, which is easiest to make X. "The sum of a number and 8" will mean that 8+something is the sum so they have to go in parenthesis... giving you
4/3*(x+8)=24
now just solve for X, remembering to use the reverse of PEMDAS, since you're solving for the variable.
remove what is furthest away to the X first.
x+8=24*3/4
x+8=18
x=18-8
x=10
Now, remember to always go through and replace your variable with its value and solve. if it is not equal on both sides, retry the problem because you may have missed a small +, -, or * somewhere!
Hope this helped:)