Idon't understand #5 and #7. my friend tried to explain this to me but i didn't get it.

When using the linear combination metho e linear combination method to solve a system of linear equations, the four options are:

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.

Drag the tiles to the boxes to form correct pairs. not all tiles will be used. match each set of vertices with the type of quadrilateral they form