①(x+3)(x+4)=x2+7x+12;②(x+3)(x﹣4)=x2﹣x﹣12;
③(x﹣3)(x+4)=x2+x﹣12;④(x﹣3)(x﹣4)=x2﹣7x+12
根据你发现的规律,若(x+p)(x+q)=x2﹣8x+15,则p+q的值为( )