For addition and subtraction, use the standard + and – symbols respectively. For multiplication, use the * symbol. A * symbol is not necessary when multiplying a number by a variable. For instance: 2 * x can also be entered as 2x. Similarly, 2 * (x + 5) can also be entered as 2(x + 5); 2x * (5) can be entered as 2x(5).

: https://www.wyzant.com/resources/lessons/math/algebra/calculators/equation?equation=6x+-+2+%2B+2x+%3D+-2+%2B+4x+%2B+8