PLeAsE hElP mE... wut is 20 x 87

For which rational expression is -2 an excluded value of x?

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?

The graph shows the distance kerri drives on a trip. what is kerri's speed?