[Question]The region east of plain A is 50 square miles less than the region east of plain B. If plain B has 200 square miles, how many square miles do the plains have in total?
[Answer]The region of plain A has a total of 200 - 50 = 150 square miles. The total number of square miles for both plains is 150 square miles for plain A + 200 square miles for plain B = 350 square miles. The answer is 350.

[Question]Sara sent letters to her friend in China every month. She sent 6 letters in January, 9 letters in February, and in March she sent triple the number of letters she sent in January. How many letters does Sara send?
[Answer]Combining January and February, Sara sent 6 + 9 = 15 letters. In March, she sent 3 * 6 = 18 letters. Altogether, Sara sent 15 + 18 = 33 letters. The answer is 33.

[Question]A chef needs to make french fries. He can get 25 fries out of 1 potato. He has 15 potatoes and he needs 200 fries. How many potatoes will he have leftover?
[Answer]To make 200 fries he will need 200 / 25 fries per potato = 8 potatoes. He has 15 potatoes - 8 potatoes = 7 leftover potatoes. The answer is 7.

[Question]Sara's house is 100 square feet larger than 2 times Nada's house. If Sara's house is 1000 square feet, how many square feet is Nada's house?
[Answer]
Let the number of square feet in Nada's house be y. 2y + 100 = 1000. 2y = 900. Meaning, y = 450 square feet. The answer is 450.