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Step-by-step explanation:
the answer would be= -2fx+3x^2+15+a/fx
-10 is equal to 5 subtracted from a number
Assume that the number is x
So the equation will be

we put x at first because in subtraction the number after the word "from" comes first
Now let us find x
We need to move 5 to the left side to find x, so add 5 to both sides

The number is