Someone pls help this is an emergency

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?

In the 30-60-90 triangle below side s has a length of and side r has a length

Pls! does anybody know a shortcut for answering these types of questions in the future?