Question 8287
Because the moon’s gravity is much less than the earth’s, an individual standing on the earth would weight 6 times what she would weigh on the moon. Kate weighs twice as much as Stephanie when they stand on the moon. If the total of their weights on the moon is 36 pounds, what does Stephanie weigh on the earth? 


kate=2 times heavier than stephanie.  
stephanie=s
Kate=2s


The total...or the sum...of their weight is 36.  we must add kate & stephanie's weight and equate it to 36 lbs.

s+2s=36
3s=36     <--divide both sides by 3 to isolate  "s"
{{{3s/3}}}={{{36/3}}}
s=12


since stehanie is S, she weighs 12 pounds on the moon.  But, since the problem asks how much she'll weigh on earth, we have to go back to the earth & moon weight ratio: 


moon weight=x
earth weight=6x


multiply 12 by 6 to find stephanie's earth weight:  12*6=72


Stephanie weighs 72 pounds on earth.