Find the amount (future value) of the ordinary annuity. $750/month for 16 years at 4%year compounded monthly

Achemist has 200 ml of a 10% sucrose solution. she adds x ml of a 40% sucrose solution. the percent concentration, y, of the final mixture is given by the rational function: the chemist needs the concentration of the final mixture to be 30%. how many milliliters of the 40% solution should she add to the 10% solution to get this concentration?

We just started the introduction into circles and i have no idea how to do this.

Use the given information to determine the exact trigonometric value.