Question: Mary has 300 sheep and Bob has double the number of sheep as Mary plus another 35. How many sheep must Mary buy to have 69 fewer sheep than Bob? Think carefully first, then make a decision:
Bob has (300 * 2) + 35 = 635 sheep. For Mary to have 69 sheep fewer than Bob she must own 635 69 = 566 sheep. As Mary has already 300 sheep she must buy 566 300 = 266 sheep. So the answer is 266.