Don put $3,000 in a savings account with an interest rate of 5% for three years. If the interest is compounded annually, how much money will he have at the end of the three years?

Compounded anually means

if you put x in at y percent then

you calculate like this

if you put in x at y percent then the money you earn is

x + (x times y) = z=first year

second year=z + (z times y) = s

third year=s + (s times y) = t

percent means parts out of 100 so 5%=5/100=0.05

'of' can be translated as multiply

so

3000 + (3000 times 0.05) = 3150=fisrt year

3150 + (3150 times 0.05) = 3307.5=second year

3307.5 + (3307.5 times 0.05) = 3472.88=tird year

he will have 3472.88 at end of 3 years