Answer:
Half off is better, you save 5 dollars.
If you don't see how I wrote those equations let me know because that's the main takeaway from this exercise, not as much the other stuff I did below that.
Step-by-step explanation:
Kinda a system of equations problem. Let's set them up.
The first one is buy 1 pair at full price get the scond pair at half price. if we use price of the first as P1 and price of the second as P2 this works out to:
P1 + .5*P2
The second offer is but one pair at ful price then the second has 10 dollars deducted. This will look like:
P1 + P2-10
Let me know if you don't get how I made those expressions. Now you could plug the price the question gives you into both and just see which is smaller, but I'm going to show you when the dals switch with whch is better.
Again, feel free to just plug in what I've given you so far.
The trick is to set them equal to each other.
P1 + P2 - 10 = P1 + .5P2 Subtract P1 from both sides
P2 - 10 = .5P2 divde both sides by .5 (or multiply by 2, same thing.)
2P2 - 20 = P2 add 20 to both sides
2P2 = 20 + P2 subtract P2 from both sdes
P2 = 20
So when P2 equals 20 the deals are the same. if P2 is below 20 the 10 dollas off is the better deal, and if P2 is greater than 20 the half off deal is better.
Since both shoes cost 30 we don't have to pick which is which, and since it is greater than 20 the half off deal is better. Now plug into both equations to find by how much.
P1 + .5P2 = 30 + .5*30 = 45
P1 + P2 - 10 = 30 + 30 - 10 = 50
50-45 = 5
So you save 5 dollars
