Question: Tonya has $150.00 on her credit card. If she leaves any balance on her card at the end of the month, she is charged 20% interest. If she makes a $50.00 payment on her card, what will be the new balance?
Answer with step-by-step thinking: Her card has a $150.00 balance and she makes a $50.00 payment so the new balance is 150 - 50 = $100.00. She didn't pay it off so she is charged 20% interest on her $100.00 balance so the interest is .20 * 100 = $20.00. Her balance was $100.00 and she was charged $20.00 in interest so her new balance is 100 + 20 = $120.00.
So the answer is 120.


Question: David swims the 100-meter freestyle in 48 seconds. He swims the 100-meter backstroke 4 seconds slower than he swims the 100-meter freestyle, he swims the 100-meter butterfly 3 seconds slower than he swims the 100-meter backstroke, and he swims the 100-meter breaststroke 2 seconds slower than he swims the 100-meter butterfly. What is the combined length of time, in seconds, it would take for him to swim all four 100-meter events (the freestyle, the backstroke, the butterfly, and the breaststroke)?
Answer with step-by-step thinking: David swims the 100m backstroke at 48 + 4 = 52 seconds. He swims the 100m butterfly at 52 + 3 = 55 seconds. He swims the 100m breaststroke at 55 + 2 = 57 seconds. IN total, it would take David 48 + 52 + 55 + 57 = 212 seconds.
So the answer is 212.


Question: Susan had a sum of money. She spent 1/5 of it in September, 1/4 of it in October, and $120 in November. After spending these amounts of money, she still had $540 left. How much money did she have at first?
Answer with step-by-step thinking:
Let X be the amount Susan had originally. Susan spent 1 / 5 * X in September, 1 / 4 * X in October, and $120 in November. Susan has X - 1 / 5 * X - 1 / 4 * X - $120 = $540 left. Combining like terms, we get 11 / 20 * X - $120 = $540. Adding $120 to both sides, we get 11 / 20 * X = $660. Dividing both sides by 11 / 20 we get X = $1200.
So the answer is 1200.