SOLUTION: a thief steals a number of plants from a nursery. on the way out he meets three guards one after another. to each guard he is forced to give half of the plants he still had plus 2.

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Question 1120494: a thief steals a number of plants from a nursery. on the way out he meets three guards one after another. to each guard he is forced to give half of the plants he still had plus 2. he leaves with 15. how many were originally stolen?
Found 2 solutions by solver91311, josmiceli:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Hint: Work backwards. He had 15 at the end. Add 2 and then double the result. Repeat the process 2 more times.


John

My calculator said it, I believe it, that settles it


Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = number originally stolen
After 1st guard, he has
+x+-+x%2F2+-+2+
After 2nd guard, he has
+x%2F2+-+2+-+x%2F4+%2B+1+-+2+
After the 3rd guard he has
+x%2F4+-+3+-+x%2F8+%2B+3%2F2+-+2+
And
+x%2F8+-+7%2F2+=+15+
+x%2F8+=+7%2F2+%2B+30%2F2
+x%2F8+=+37%2F2+
+x+=+4%2A37+
+x+=+148+
He stole 148 plants
———————-
Check
+148+-+74+-+2+=+72+
+72+-+36+-+2+=+34+
+34+-+17+-+2+=+15+
OK