What are 3 heterogenous fractions for 9/5

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

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 parabola x = y² - 9 opens: a.)up b.)down c.) right d.)left