Please help me I have no idea about this, picture above or below. ¯\_(ツ)_/¯

For the first one, the error is that he added 6x and -2 (but they aren't like terms). Correct value is 11/3

For the second one, the error is that he didn't minus 3 by -8 properly. The correct value is -3

For the third one, the error is that he didn't expand the brackets properly ( he didn't multiply four by 2). Correct value is -2

For the fourth one, the error is that he didn't plus 3 and 2 together properly. Correct value is 6

For the fifth one, the error is that he only divided six by three, when he was supposed to divide six by one over three. Correct answer is 18

For the sixth one, the error is that he didn't multiply negative two by negative three properly. Correct answer is positive four.
Hope this helps :)