How do you determine whether to use substitution or elimination. give an example of a system that you would solve using each method?

And employee salary increased by $4500 which represents a 15% raise what is the rate of the increase

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?

Tom had a total of $220 and he spent $35 on a basketball ticket . what percent of his money did he have left?