91Ó°ÊÓ

In the following exercises, add.

$\frac{7m}{2m+n}+\frac{4}{2m+n}$

Simplify$\frac{x^2+x-2}{1-x^2}.$

Solve: $m=\frac{y-5}{x-4}$ for$y$.

Solve:$m=\frac{y-1}{x+5}$for$y.$

Solve: $\frac{1}{a}+\frac{1}{b}=c$ for$a.$

Solve:$\frac{2}{x}+\frac{1}{3}=\frac{1}{y}$for$y.$

Solve the proportion$\frac{y}{y+55}=\frac{3}{8}$.

Solve the proportion$\frac{z}{z-84}=-\frac{1}{5}$.

Pediatricians prescribe 5 milliliters (ml) of acetaminophen for every 25 pounds of a child’s weight. How many milliliters of acetaminophen will the doctor prescribe for Emilia, who weighs 60 pounds?

For every 1 kilogram (kg) of a child’s weight, pediatricians prescribe 15 milligrams (mg) of a fever reducer. If Isabella weighs 12 kg, how many milligrams of the fever reducer will the pediatrician prescribe?