Of the 90 people on William's bus, 3/5 were Dutch. Of the 1/2 of the Dutch who were also American, 1/3 got window seats. What's the number of Dutch Americans who sat at the windows? Give the rationale and then the answer.
Let's think step by step. On the bus, the number of Dutch people was 3 / 5 of the total number, a total of 3 / 5 * 90 = 54 people. Out of the 54 people who were Dutch, 1 / 2 were Dutch Americans, a total of 1 / 2 * 54 = 27 people. If 1 / 3 of the passengers on the bus identifying as Dutch Americans sat at the windows, their number is 1 / 3 * 27 = 9.. The answer is: 9.

If Ruby is 2 centimeters shorter than Pablo. Pablo is 70 centimeters taller than Charlene. Janet is 62 centimeters tall and Charlene is twice that tall. How tall is Ruby? Give the rationale and then the answer.
Let's think step by step. Charlene is 2 * 62 cm = 124 cm tall. Pablo is 70 cm + 124 cm = 194 cm tall. Ruby is 194 cm - 2 = 192 cm tall.. The answer is: 192.

John ends up damaging his hearing aids. He needs to replace both of them. They cost $2500 each. Insurance covers 80% of the cost. How much does he personally have to pay? Give the rationale and then the answer.
Let's think step by step. The cost of the hearing aids is $2500 * 2 = $5000. So insurance covers $5000 * .8 = $4000. That means it cost him $5000 - $4000 = $1000.. The answer is: 1000.