You already know the number is -3. 
Four less than three times the sum of a number and four. 
So, four less than will be at the end of the formula. The beginning of the formula is 3 times. 
So it looks like this so far
3( )-4 Now let's look at "the sum of the number (-3) and 4. 
So this is how it looks now
3(-3+4)-4
Remember, do inside the parenthesis first, then multiply, and lastly your subtraction.