To simplify the expression, we just have to reduce like terms. In this case, -10x and +3x are like terms because they have the same variable with the same exponent, we just have to subtract them.
[tex]2x^2-10x+3x-15=2x^2-7x-15[/tex]Therefore, the simplified expression is
[tex]2x^2-7x-15[/tex]
