What two numbers multiply to -30 and add to -7

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?

This race was first held in 1953 on august 16th. every decade the race finishes with a festival. how many years is this?

On monday, the water was shut off 3 times for 1/4 hours, 2/3 hours, and 1-3/4 hours, respectively. what was the tireless number of hours the water was off?