Question: Explain how to solve this math problem: The dog toys Samantha buys for her dog are "buy one get one half off" and all cost $12.00 each. She buys 4 toys.  How much does she spend on dog toys?
Answer: 
If she buys 1 toy at $12.00 she gets the 2nd toy 1/2 off, the 2nd toy is 12*.5 = $6.00
1 full-priced toy is $12.00 and 1/2 priced toy is $6.00 so these 2 toys come to 12+6 = $18.00
She buys 2 more toys that are "buy one get one 1/2 off" so all total she spends 2*18 = $36.00