The Moon is about 240,000, or x 10 miles from earth

Step-by-step explanation:

240,000 = 24 x 10^4

24 followed by 4 zeros = 24 x 104

Just make the number of zeroes be the exponent for 10

24 = 24 x 10^0

240 = 24 x 10^1

2400 = 24 x 10^2

24000 = 24 x 10^3

240,000 = 24 x 10^4 miles

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.