The formula for percentage increase I (given as a decimal) of an investment is I=\frac{S-P}{P} , where P is the purchase price and S is the sale price. You sell a stock at a price of $75, earning a percentage increase of 25%. What was the purchase price of the stock?

Onnie is considering doing some long term investing with money that she inherited. she would like to have $50,000 at the end of 30 years. approximately how much money would lonnie need to put into an account earning 6% interest compounded annually in order to meet her goal?