Unfortunately, I can't do it on a graph here, but I will do it algebraically. The solution on the graph will be the point of intersection of the two lines representing the equations. y + 2.3 = 0.45x . . . . . (1) -2y = 4.2x - 7.8 . . . . . (2) From (2), y = 3.9 - 2.1x substituting for y in (1), we have: 3.9 - 2.1x + 2.3 = 0.45x 2.55x = 6.2 x = 6.2/2.55 = 2.4 y = 3.9 - 2.1(2.4) = 3.9 - 5.04 = -1.2 Therefore, solution is (2.4, -1.2)
Start by moving the x and the y to the same side and moving the number across the equal sign in both equations. We should now have y-0.45x=-2.3 and 2y+4.2x=7.8. We can use the elimination method by multiplying the first equation by -2 to get -2y+0.9x=4.6 and 2y+4.2x=7.8. From there, add the two equations together, eliminating y (-2+2=0). We now have 5.1x=12.4; divide both sides by 5.1 to get x=2.4. Then, in any of the two equations, let's use y-0.45x=-2.3, substitute x with 2.4. Now we have y-1.08=-2.3. Add 1.08 to both sides to get y=-1.22; round that to the nearest tenth to get -1.2.
Answer: 440 grams for 1.54 is the better value
Explanation:
Take the price and divide by the number of grams
1.54 / 440 =0.0035 per gram
1.26 / 340 =0.003705882 per gram
0.0035 per gram < 0.003705882 per gram
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