8^2+9(12/3x2)-7 explain each of your steps

8^2 + 9 * (12/3 * 2) - 7 <--- First thing that PEMDAS is Parenthesis. But oh wait there are both division and multiplication, which one comes first? Division, so you go that

8^2 + 9 * (4*2) -7 <--- Go ahead and multiply now whats still inside the parenthesis

8^2 + 9 * 8 - 7 <--- Next is the exponents, you gotta remember that 8 to the second power is not 8*2 its 8*8

64 + 9 * 8 - 7 <--- Since there isn't division, just go and multiply 9*8

64 + 72 - 7 <--- I see addition first! So add 64 + 72

136 - 7 <--- Lastly subtract

129 <--- That is your answer :) Hope this helped