Describe how you would use a yardstick to measure a length of a rug

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?

Aline has a slope of 1/4 and passes through point (0.4,-1/2). what is the value of the y-intercept?

Add the fractions, and simply the result to lowest terms. 2/3 + 2/7= ?