A couple just had a baby and they want to save for its education. So they open a

savings account earning a 4% annual rate, where they will deposit x% of their annual income

at the end of each year for the next 18 years. Assume their current annual income is $150,000,

and it grows by 5% each year, and their goal is to have saved $100,000 in 18 years from now.

Find the value of x.