[Image of 4 integers A, B, C, and D on a number line]
The integers A, B, C, and D shown on the number line above are all equally spaced. If C and D are equal to 5^12 and 5^13, respectively, what is the value of A?
- 1. 5^11
2. 5^10
3. -5^12
4. (-7)5^12
5. (-12)5^13
I can set up the equation: [spoiler]D minus three times the difference between C and D (or) 5^13 - 3(5^13-5^12) = A.[/spoiler] But after that, I'm lost with the algebra.
Below is the algebra for the right answer:
[spoiler]5^13 - 3(5^13 - 5^12)
5^13 - 3[5^12(5 - 1)]
5^13 - 3(5^12)(4)
5(5^12)- 12(5^12)
(-7)5^12
The correct answer is D.[/spoiler]
Can someone explain what operations are taking place in the first 2 lines?
Thanks in advance.