I need help please help me now

How many sides does a regular polygon have if each exterior angle measures 72a.3b.4c.5d.6

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?

Will gve pints stars and brainliest