How do I write a - b as an algebraic expression using words

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?

Question 10jur's car can travel 340 miles on 12 gallons. jack's car can travel 390 miles on16 gallons. which person has the best mileage (miles per gallon) and what istheir mileage?

Iwill give ! if m∠a=59 and m∠3=81°, what is m∠b? m∠b= _[blank]_°