Jason works as an administrative assistant for a local lawyer's office. the office is running low on pens and notepads, so he is asked to buy $150 worth of pens and notepads. pens cost $1, and notepads cost $2. if the number of pens he buys is represented by x and the number of notepads he buys is represented by y, the situation can be given by x + 2y = 150, where 0 ≤ x ≤ 150, 0 ≤ y ≤ 75 and x and y can take only integer values.