"He has 4 more $5 notes than $2 notes.", so subtract the 4 more $5 notes from $76.

76 - 4 x5 = 76 - 20 = 56

Then, in the remaining $56, there is an equal number of $5 note and $2 notes. That means for each $5 note, there must be one $2 note. We put one $5 note and one $2 note in one group. Then check there are how many groups in the remaining $56.
56 / (2+5) = 56 / 7 = 8

So Ali has 8 $2 notes and 12 $5 notes.

To draw math models to illustrate the math questions is a good way to teach kids the problem sums. Because it visually represents the information in the problem and then kids can easily understand and write down the correct calculations.