What does the key word as long mean

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?

Which of the following points is collinear with (-2,1) and (0,3)

Solve 2x+y=3 x+y=5 in substitution method