a) Saturn is 9.1 * 10^8 miles from the sun and earth is 9.3 * 10^7 miles from the sun. By what distance is one planet closer to the sun than the other planet?

8.17 * 10^8

Step-by-step explanation:

Saturn is 9.1 * 10^8 miles from the sun, and earth is 9.3 * 10^7 miles from the sun. From this, we can see that Saturn is much farther from the sun than the earth.

To find the distance of one planet closer to the sun than the other planet, we can subtract 9.3 * 10^7 from 9.1 * 10^8.

Original expression: 9.1 * 10^8 - 9.3 * 10^7

Convert both sides to 10^7: 91 * 10^7 - 9.3 * 10^7

Subtract: 81.7 * 10^7

Simplify: 8.17 * 10^8

Let me know if this helps!

i think it's eleven too, don't woosh me here, but according to the "experts" it's 2.

the proof starts from the peano postulates, which define the natural

numbers n. n is the smallest set satisfying these postulates:

  p1.   1 is in n.

  p2.   if x is in n, then its "successor" x' is in n.

  p3.   there is no x such that x' = 1.

  p4.   if x isn't 1, then there is a y in n such that y' = x.

  p5.   if s is a subset of n, 1 is in s, and the implication

      (x in s => x' in s) holds, then s = n.

then you have to define addition recursively:

  def: let a and b be in n. if b = 1, then define a + b = a'

      (using p1 and p2). if b isn't 1, then let c' = b, with c in n

      (using p4), and define a + b = (a + c)'.

then you have to define 2:

  def:   2 = 1'

2 is in n by p1, p2, and the definition of 2.

theorem:   1 + 1 = 2

proof: use the first part of the definition of + with a = b = 1.

      then 1 + 1 = 1' = 2   q.e.d.

note: there is an alternate formulation of the peano postulates which

replaces 1 with 0 in p1, p3, p4, and p5. then you have to change the

definition of addition to this:

  def: let a and b be in n. if b = 0, then define a + b = a.

      if b isn't 0, then let c' = b, with c in n, and define

      a + b = (a + c)'.

you also have to define 1 = 0', and 2 = 1'. then the proof of the

theorem above is a little different:

proof: use the second part of the definition of + first:

      1 + 1 = (1 + 0)'

      now use the first part of the definition of + on the sum in

      parentheses:   1 + 1 = (1)' = 1' = 2   q.e.d.