Question: Sarah's age is equal to three times Mark's age minus 4. Mark is four years older than Billy. Billy is half Ana's age. If Ana will be 15 in 3 years, how old is Sarah?
Answer: First figure out how old Ana is right now by subtracting 3 from 15: 15 - 3 = 12. Next, figure out how old Billy is by dividing Ana's age by 2: 12 / 2 = 6. Now figure out how old Mark is by adding 4 to Billy's age: 6 + 4 = 10. Now, to figure out Sarah's age, first multiply Mark's age by 3: 10 * 3 = 30. Finally, subtract 4 from triple Mark's age to find Sarah's age: 30 - 4 = 26. The answer is 26.

Question: John puts $25 in his piggy bank every month for 2 years to save up for a vacation. He had to spend $400 from his piggy bank savings last week to repair his car. How many dollars are left in his piggy bank?
Answer: He saved money for 2 years, which is equal to 12 x 2 = 24 months. The amount of money he saved is $25 * 24 = $600. But he spent some money so there is $600 - $400 = 200 left. The answer is 200.

Question: Ravi has some coins. He has 2 more quarters than nickels and 4 more dimes than quarters. If he has 6 nickels, how much money does he have?
Answer: Ravi has 6 + 2 = 8 quarters. He has also 8 + 4 = 12 dimes. A nickel is worth 5 cents so Ravi's nickels amount to 6 x 5 = 30 cents. A quarter is worth 25 cents so his quarters amount to 8 x 25 = 200 cents. A dime is worth 10 cents so his dimes amount to 12 x 10 = 120 cents. therefore, Ravi has 30 + 200 + 120 = 350 cents. The answer is 350.

Question: Marla has a grid of squares that has 10 rows and 15 squares in each row. She colors 4 rows of 6 squares in the middle of the grid with red. She colors all squares on the first 2 and last 2 rows with blue. Then she colors the rest with green. How many squares does Marla color green?
Answer:
There are 10 x 15 = 150 squares in a grid. 4 x 6 = 24 squares are colored red. There are 2 + 2 = 4 rows that are all blue. Thus, a total of 4 x 15 = 60 squares are colored blue. 24 + 60 = 84 squares are color red or blue. Therefore, 150 - 84 = 66 square are green. The answer is 66.