ADDING AND SUBTRACTING SIMPLE FRACTIONS WITH VARIABLES

by Dr. Carol JVF Burns (website creator)
Follow along with the highlighted text while you listen!
• PRACTICE (online exercises and printable worksheets)
Want more details, more exercises?
• Need some basic practice with adding and subtracting fractions first?

EXAMPLES:
Question: Combine into a single fraction: $\displaystyle\,\frac{2x}{5} + \frac{1}{3}$
Solution:   Notice that the least common denominator is $\,15\,$.

$\displaystyle \cssId{s10}{\,\frac{2x}{5} + \frac{1}{3}} \cssId{s11}{\ \ =\ \ \frac{2x}{5}\cdot\frac{3}{3} + \frac{1}{3}\cdot\frac{5}{5}} \cssId{s12}{\ \ =\ \ \frac{6x}{15} + \frac{5}{15}} \cssId{s13}{\ \ =\ \ \frac{6x+5}{15}}$
Question: Combine into a single fraction: $\displaystyle\,\frac{2}{9t} - \frac{1}{6}$
Solution:   Notice that the least common denominator is $\,18t\,$.

$\displaystyle \cssId{s19}{\,\frac{2}{9t} - \frac{1}{6}} \cssId{s20}{\ \ =\ \ \frac{2}{9t}\cdot\frac{2}{2} - \frac{1}{6}\cdot\frac{3t}{3t}} \cssId{s21}{\ \ =\ \ \frac{4}{18t} - \frac{3t}{18t}} \cssId{s22}{\ \ =\ \ \frac{4-3t}{18t}}$
Master the ideas from this section

When you're done practicing, move on to:
Divisibility Equivalences

CONCEPT QUESTIONS EXERCISE: