Question 752348
This only requires knowing order of operations.  The confusion I find is in how you arranged your rendering tags.  


I will assume you mean this:
{{{3 - (-7)*3^2  + 37 + (-7)^2}}}


Parentheses first.
Just as you have,
{{{3 - (-7)*3^2  + 37 + (-7)^2}}}


EXPONENTS.
{{{3-(-7)*9+37+49}}}


MULTIPLICATIONS AND DIVISIONS.
{{{3-(-63)+37+49}}}


And you can finish...?