Answer:
18
Step-by-step explanation:
You want a number that results in 48 after 12 is added to its double.
Undo
Working backward from the result, we find the doubled number is ...
48 -12 = 36
Then the original number is ...
36/2 = 18.
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Check
When 18 is doubled and 12 is added, the result is 36+12 = 48, as required.
