is there a difference in the result between 48/2(9+3) and 48/2*(9+3) ?

"what i'm trying to say is, does the sign of multiplication "*" affect the precedence of equation?"

No. Implicit multiplication (I.e. multiplication without an explicit *) is still multiplication.

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\(\frac{48}{2}*(9+3) is not \frac{48}{2*(9+3)}\)

But the way you wrote it, its the same.

what i'm trying to say is, does the sign of multiplication "*" affect the precedence of equation?
Knowing that parentheses has the highest priority, so this (9+3) has to be done first for sure. However, does this part 2(12) has more priority than 2*(12) ? 
in other words, does the sign "*" (wheather it exists or not in the equation) affect the precedence of the operators?