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?
The region of plain A has a total of 200 - 50 = 
<gadget id="calculator">200-50</gadget>
<output>150</output>
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 = 
<gadget id="calculator">150+200</gadget>
<output>350</output>
350 square miles.

<result>350</result>