Can you help solve this please.

How many different ways can you make change for $.50 using only nickels,dimes, and quarters?

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 amount spent on food and drink by 20 customers is shown below what is the modal amount spent ?