During we 14 of precalculus 11, we started off Monday with our test on unit 8, and began the next 4 days learning the first 3 lessons of unit 7. 7.1 was on equivalent rational expressions, 7.2 was on multiplying and dividing rational expressions, and 7.3 was on adding and subtracting rational expressions.
One thing I learned from lesson 7.2 and 7.1, was that in a long fractional expression, numbers can be canceled out by dividing before the fractions are even combined or multiplied.
For example, the expression 10/15 * 3/2 * 4/6
can be simplified down by dividing common factors of denominators and numerators.
10 and 2 = 5/1
15 and 3 = 1/5
then 5/5 = 1
leaving only the 4/6 making that expression equal to 2/3.