I do believe Jane is going to have more Crayons left.
In this problem we can see that Jane has 4/9 of a box left, this means that if we convert it into a fraction with like terms with 3/7 we can do a comparison.
The only numbers 7 and nine share is 63 so we can convert the denominators to fractions of 63.
If we do so 4/9 (multiply both sides by 7) changes that to 28/63
3/7 (multiply both sides by 9) changes that to 27/63
Since Jane has 28 out of 63 crayons left and Scott has 27 out of 63 then Jane has more.