Answer:
3 tents hold 2 campers
Step-by-step explanation:
The given relations can be expressed as a single equation in the number of 2-camper tents.
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Let x represent the number of 2-camper tents. Then the number of 4-camper tents is 6-x, and the total number of campers in tents is ...
2x +4(6 -x) = 18
-2x +24 = 18
-2x = -6 . . . . . . subtract 24
x = 3 . . . . . . . divide by -2
Exactly 3 tents hold 2 campers.
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Additional comment
The other 3 tents hold 4 campers.
Another way to consider this is to assume that all tents hold 2 campers, and then realize there are 18 -6×2 = 6 campers left over. If these are placed 2 per tent, then there will be 6/2 = 3 tents with 4 campers. The remaining 3 tents will have 2 campers.