what are the slope and the y-intercept of the linear function that is represented by the graph?

mc002-1.jp
the slope is mc002-2.jp and the y-intercept is 3.
the slope is mc002-3.jp, and the y-intercept is 4.
the slope is mc002-4.jp and the y-intercept is 3.
the slope is mc002-5.jp, and the y-intercept is 4.
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Saline iv fluid bags cost $64.20 for 24, 1000 ml bags from one supplier. a new supplier sells 500 ml bags for $2 each. the hospital uses about 10,000, 1000 ml bags each month. nurses report that about half of the bags are more than half full when they are discarded. if you are going to use only one supplier, which size bag provides the best deal, and how much will you save each month? compare the cost of the new supplier to the current one.

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

What are the solutions of the system? solve by graphing. y = x^2 + 3x + 2 y = 2x + 2