At 8/4/11 04:02 PM, MaestroCC wrote:
"You saw a shirt for Â£97. You didn't have the cash, so you borrowed Â£50 from your mom and Â£50 from your dad = Â£100. You bought the shirt and had Â£3 change. You gave your dad Â£1 and your mom Â£1 and kept the other Â£1 for yourself."
Start: 50+50 = 100. (Borrowed, you have this money, it is credit in your pocket)
Buy shirt, 100 - 97 = 3 (You spent 97, you have 3 in your pocket.
The 49+49 part is where the calculation is incorrect. There is no 49+49, there is 50+50 with 3 remaining due to losing 97. The 49+49 of DEBT + 1 of CREDIT does not = 98, it = 97.
You _OWE_ your parents 49 each, which means the number is actually -49 + -49 which = -98. The debt is 49 to each parent because you already gave them each 1 in change, right? And you have 1 left over which you kept. So knowing our current number is -98 (as in, 98 in debt, not 98 in credit) and adding that 1 that you kept for yourself (which is credit) it becomes -97.
+1 (this is your missing 1 pound - the one you kept)
Which leaves you with -97, which was how much you spent on the shirt.