You have $55,000 in savings account that pays 2% intrest per year. the inflation rate that year is 3.24%. how much do you make in intrest each year

Your interest formula is given to you.

Interest in a year = principal (the amount invested) * rate (the interest rate) * period (the time you're measuring)

Interest = 55,000 * 2% * 1 year = 55,000 * 0.02 * 1 = $1,100

How much would you need to have made for your spending power to keep with inflation? Your interest rate would have needed to match the inflation rate, otherwise prices are going up faster than you're saving.

Required interest = 55,000 * 3.24% * 1 year = 55,000 * 0.0324 * 1 = $1,782

How much buying power did you lose? The difference between your required interest and your actual interest.
Buying power lost = 1,782 - 1,100 = $682. You lost this much in buying power.

Hope that helped :)