Can you solve this using substitution -8x-3y=21, y=3x+10

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 perimeter of a stage is 116 feet. it is 17 feet wide. how long is it?

Which representation has a constant of variation of -2.5