Question. Tom cannot afford a normal doctor, so he goes to a discount clinic that is 70% cheaper.  It takes two visits, though, instead of 1.  A normal doctor charges $200 for a visit.  How much money does he save?
Answer. 80
What step-by-step reasoning justifies that answer?
Reasoning: Each of Tom's visits was 200 * .7 = $140 cheaper. So he paid $200 - $140 = $60 per visit. That means he paid $60 * 2 = $120. So he saved $200 - $120 = $80.