102 - [3(2+7)+8]
102 - [3x2+3x7+8]
102 - [6+21+8]
102 - 35
67
now for the steps:
1)you always do multiplication first which was 3(2+7) ,which is 3x2+3x7
2)then add them which is 6 +21
3)add all of the three numbers 6+21+8 = 35
4)then you take out the brackets and subtract your numbers which is
102 - 35 = 67
