Set up an equation to solve.
70% of original price equals $550, the amount Susan is paying.
0.70x = 550
Sample Equation: 3x - 3 = 27
Multiple step:
3x - 3 = 27
<u> + 3 +3</u> Step1. Remove the -3 by adding 3 to both sides
3x = 30
<u>÷3 ÷ 3</u> Step2. Remove the multiplicand 3 by dividing both sides by 3
x = 10
To check: substitute x by its value
3x - 3 = 27
3(10) - 3 = 27
30 - 3 = 27
27 = 27
The scale factor is 1/2 or .5 because 200*.5=100 and 100*.5=50 and so on