Please demonstrate !!

1. Your parents start saving for your sister's college education. She will begin college when she turns age 18 and will need $4,000 at that time and at the end of each of the following 3 years. They will make a deposit at the end of this year in an account that pays 6% compounded annually, and an identical deposit at the end of each year with the last deposit occurring when she turns age 18. If an annual deposit of $1,484 will allow them to reach their goal, how old is your sister now? Which dimension of Time Value of Money do you use to solve this problem? [Think of the critical juncture, which is age 18 of your sister at which two money series are met and equal.