Answer this question:At least a third of Fred's marbles are dark blue. All of the rest are red, except for 4 that are green. If he has 63 marbles, how many of them are red?
Fred has 63 / 3 = 21 dark blue marbles. Fred has 63 - 21 = 42 red and green marbles. Fred has 42 - 4 = 38 red marbles.
The answer is 38.

Answer this question:Paul's grades last semester were very bad. To encourage him, Paul's dad promised him $5 for every B+ he gets in his next scorecard and twice that amount for every A. If Paul obtains at least two A+ he'll double the previous rewards and would receive a flat $15 for every A+ obtained (with no extra bonus). If there are 10 courses with grades in Paul's scorecard, what's the maximum amount he could receive from his dad?
We know Paul would get $5 for a B + . However, we know this could be (2x) doubled if he obtains at least two A + . This means 2 * $5 = $10 for a B + if Paul gets at least two A + . We know Paul would get twice the reward of a B + if he gets an A. This means 2 * $5 = $10 for every A. However, we know his reward for every A could be (2x) doubled if he obtains at least two A + . This means 2 * $10 = $20 for every A if Paul gets at least two A + . We learn here then that Paul will get a higher reward for obtaining A grades ($20) than getting A + grades ($15) as long as he's able to score at least two A + . To maximize his payout, Paul will need to get only (2) two A + from his 10 courses. Therefore he should aim to get an A in the remaining 10 - 2 = 8 courses. Assuming Paul can get two A + and eight A in his next scorecard his total payout would be 2 * $15 + 8 * $20. This translates into $30 + $160 or $190.
The answer is 190.

Answer this question:A mother planted a 16-inch tree on her son's first birthday. On the day the tree was planted, the boy was 24 inches tall. If the tree grows twice as fast as the boy does, how tall will the tree be by the time the boy is 36 inches tall?
The boy grew 36 - 24 = 12 inches since the tree was planted. Since the tree grows twice as fast as the boy, it will have grown 12 * 2 = 24 inches during this time period. Thus, the final height of the tree is 16 + 24 = 40 inches.
The answer is 40.

Answer this question:The age of Gladys is equal to twice the sum of the ages of Billy and Lucas. Billy is 3 times younger than Gladys who is 30 years old now. How old will Lucas be three years from now?
Billy's age is 30 / 3 = 10 years old. The sum of the ages of Billy and Lucas is 30 / 2 = 15. So, Lucas is 15 - 10 = 5 years old now. Therefore, Lucas will be 5 + 3 = 8 years old three years from now.
The answer is 8.