Hello

let x be the amount of $2-coins

y the amount of $5-coins

Jane has 15 coins, therefor

x+y = 15

Suppose you have x=6 $2-coins, then its worth is 6*2 =$12, and you have y=9 coins (actually this is the solution) then you have 9*5 = $45. You know the difference between the worth of all your $2 coins and 5$-coins is 33$.

Hence

2x = 5y-33

(2 and 5 because of the worth of x and y)

You need to solve the equations

x+y = 15

2x = 5y-33

Regards,

Rapha