how is 6^2-8/4(3+7) 16?

Remember   PEDMAS,   or   BODMAS    or   whatever you call it in your country.

 

Brackets then exponents (I've swapped this around but it makes no difference in this question)

then   multiplication and division are equally important.  Do from left to right.

then    addition and subtraction are equally important.  Do from left to right.

 

$$\\6^2-8/4(3+7) \\\\
=36-8/4(3+7) \\\\
=36-8/4*10 \\\\
=36-2*10 \\\\
=36-20 \\\\
=16$$