sorry! i just wrote out all my work but it randomly got deleted. the answer is 8. here's how i got it:
first, i formulated two equations using the world problem:
x + y = 30
2x = 3y = 5.
then, i isolated the variables and used subsitution, then algebra, to find the value of y (which was 11, but it doesn't matter which you find first). then i found out x (which is 19). then, i found the positive difference. so the equation would be 19 - 11 = 8.