Simplify:
$$166 - [8^2 - 7^2 + \sqrt{(72 - 64 \div 8[18 \times 18 \div 324])}]$$

$$166 - [8^2 - 7^2 + \sqrt{(72 - 64 \div 8[18 \times 18 \div 324])}]$$

HERE, WE WILL USE BODMAS RULE. Bracket, Of, Division, Multiplication, Addition and Subtraction. It explains the order of operations to solve an expression. 

$$166-[8^2 - 7^2 + \sqrt{(72 - 64 \div 8[18 \times 1/18])}]$$  { solving 18/324 = 1/18}

$$166-[8^2 - 7^2 + \sqrt{(72 - 64 \div 8[1])}]$$   { solving 18*1/18}

$$166-[8^2 - 7^2 + \sqrt{(72 - 64 \div 8[1])}]$$   {solving 64/8}

$$166-[8^2 - 7^2 + \sqrt{(72 - 8)}]$$   {solving 64/8}

$$166-[8^2 - 7^2 + \sqrt{(64)}]$$   {solving 72-8}

$$166-[8^2 - 7^2 + 8]$$   {solving sqrt64}

$$166-[64-49+8]$$   {solving 72-8}

$$166-[23]$$   {solving bracket}

$$166-23$$   

$$143$$