pemdas first you do parenthesis and since yo odn't know x then you move on to exponents and if thats not in there then you go to multiplication and any number thats next toa parenthesis without a sign in between them has to be multiplied so -5 times 5 equals -5x and you also have to multiply -5 by negative 3 which is +15 because negative times negative equals positive and -x is still in there so since it's only one x it's equal to -1x and -1x +-5x equals -6x and now 7x-6x equals x+15
