ElectricPavlov

Going form R to S : 

  X   goes from -6  to 15    a distance of 21      2/3 of this is 14       add 14 to -6 to get    x = 8

  Y   goes from 19 to -5     a distance of -24     2/3 of this is -16      add -16 to 19 to get  y = 3

(8,3) 

Look for the largest prime number from 100-200 

199  would be the largest class size 

Median length will be    ( 12   +     12+16) / 2 = 20 units 

As an aside, the height can be found by 

    area = median length * height 

      80 = 20 h 

        h = 4 units 

Every SEVENTH day is a day off for J ... L has every eigth day off...   every 6x8 = 48 days they are both 'off'.

365/48 = ~7 times a year       or possibly 8 times a year if they start off with the same day off at the early beginning of the year .

As posted yesterday:

(n+2) / n    *   ( n+3)/ (n+1)  *  (n+4) / (n+2) = 10      <==== Given 

Simplifies to 

1/n * (n+3) / (n+1) * (n+4) = 10 

then:

(n^2 + 7n + 12 )/ (n^2 +n) = 10        doing the fraction division results in:

9n^2 + 3n-12 = 0 

Use Quadratic Formula with    a = 9    b= 3    and c = -12     to find  n = 1      (or - 4/3  <=== does not work) 

So the first fraction would be 3/1