Can I know if part c is correct? ​

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 circles have their centers on the x-axis? check all that apply.

Cos^2x+cos^2(120°+x)+cos^2(120°-x)i need this asap. pls me