Question

algebra

Answer 1

Here you invest $400 at the interest rate 7.25% for 7 years.
P=principal=$400; r=interest rate as a decimal fraction = 0.0725; t=time= 7 years.
Please find the formula for Amount, A, under the topic "compound interest."

Answer 2

You'll need to find the appropriate formula. Look up "compound interest."
I'm happy to guide you, but am not going to give you answers without your input.

Answer 3

i need the formula

Answer 4

Please look up "compound interest formula" on the Internet. I'd like to help you develop the ability to find the info you need yourself. I know the formula, but to just give it to you will not help you much.