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Jesse had $83 in his checking account. A month later, his checking account balance was -$21. Which expression represents the difference between the two checking account balances?
A] -|83 + 21| B] |-21 - 83| C] -|83 - 21| D] |83 - 21|
(Please just say A, B, C, or D)
Added 3+ months ago:
I feel like it's either C or D
There are several definitions of a number. One of them is "the length of a line, positive going to the right and negative going to the left." So if you draw a line going 83 units to the right of zero and 21 units to the left of zero, then you can see that the line between them is (83 + 21) units long, expressing the difference in a positive number unless you have some reason to use a negative number.
So option A or B is correct, but only if you have some reason to use the minus sign.
Get a ruler in your hands. Measure things until you start to understand how a ruler works. Measure some stuff and figure out where the center is. Say you measure a book and it's 7/8" thick. You look at your ruler and see that every eighth is divided into two sixteenths, so obviously half of 7/8" is going to be 7/16". If you write that out you have 1/2 x 7/8 = 7/16. And you notice that 1/2 is divided into 2/4 and then into 4/8 and so on, so you can convert anything to anything by multiplying all the numbers on top and then all the numbers on bottom.
Other rulers are divided into 10 and 100 parts. But an inch is still an inch, so anything on one ruler can be translated to the other ruler. A half inch on one ruler is 5/10 or 50/100 on the other. An eighth inch is just 12.5 marks when you have 100 marks per inch. A metric ruler divides an inch into 25.4 parts, so a half inch would be 12.7 of those parts. Pretty simple, isn't it? Practice this a bit and people will think you went to wizard school.
BTW I never heard of anything called "AC MATH."
