Why bother with LCD’s? **Rescaling.**

Rescaling is used to get number to the same unit.

ex) 1/8 + 3/4 = 1/8 + (3/4 * 2/2) = 1/8 + 6/8 = 1+6/8 = 7/8

**Note: You dont need to rescale for multiplication or division.**

Rule: a/b = a*k/b*k as long as k!=0,b!=0

Addition of Subtraction:

1) Rescale both

ex) a/b ± c/d

(a/b * b/d) ± (c/d * d/b)

ad/bd ± cb/db

ad±cb/bd

ex)

7/15 + 3/10

(7/15 * 2/2) + (3/10 * 3/3)

14/30 + 9/30 = 23/30