There are 4 carriages in a train and each carriage has 25 seats. If each carriage could accommodate 10 more passengers, how many passengers would fill up 3 trains?
Let's think: If each carriage had another 10 seats, each carriage would have 25 + 10 = 35 seats. The train comprises of 4 carriages and each carriage now has 35 seats; therefore a train has 35 x 4 = 140 seats. 3 trains with 140 seats each in total can take up 3 x 140 = 420 passengers.. The answer is: 420.

Dr. Harry wants to know how many candies Susan consumed during the week. Susan tells him she bought 3 on Tuesday, 5 on Thursday, 2 on Friday. If she has only 4 of them left, how many did she eat?
Let's think: She had bought 3 + 5 + 2 = 10 candies over the week. She has only 4 left which means she ate 10 - 4 = 6 candies during the week.. The answer is: 6.

John buys 3 dress shirts. They sell for $20 each. He also has to pay 10% tax on everything. How much did he pay in total?
Let's think: The shirts cost 3 * $20 = $60 before tax. The tax cost $60 * .1 = $6. So in total they paid $60 + $6 = $66.. The answer is: 66.

Ian won $100 in the lottery. He decided to use the money to pay off debts. He paid $20 to Colin. He then paid twice as much to Helen, as he had paid to Colin. Then finally, he paid half as much to Benedict, as he had paid to Helen. How much money, in dollars, does he have left after paying off debts?
Let's think:
Starting with $100, he paid $20 to Colin, leaving him with $100 - $20 = $80. Twice as much as $20 is 2 * $20 = $40. Thus, he paid $40 to Helen, leaving him with $80 - $40 = $40. Half as much to Benedict as he had paid to Helen is $40 / 2 = $20. Thus, he paid $20 to Benedict, leaving him with $40 - $20 = $20 after paying off all debts.. The answer is: 20.