(3x+5)+(6x-7 tell me the answer

Since we are adding the expressions, the parentheses can be removed without changing the signs of the terms inside.
$3x + 5 + 6x - 7$

Group the terms containing $x$ and the constant terms.
$(3x + 6x) + (5 - 7)$

Add the coefficients of the $x$ terms and add the constant terms.
$(3+6)x + (5-7)$
$9x - 2$