Can someone help with this math question

Tim open up a new saving account with a $50 deposit and plant to deposit $20 per week into the same account.write an expression to represent the total amount in his savings account.

Which of the following is missing in the explicit formula for the compound interest geometric sequence below?

Ron has 8 caps and 4 of his caps are blue. thes rest of his cap are red. how many of ron's caps are red