At the end of each day, helen throws all the change from her purse into a box. the box contains only pennies, nickels, and dimes. at the end of one week she found that the total value of the coins was $6.43. if the number of dimes was 3 more than the number of nickels and the number of pennies was 5 more than the number of nickels, how many dimes were in the box?