Start at the innermost brackets.
(5+2)=7 so replace (5+2) with 7:
{300-4[4+7²]+32/4}-31=65.
Now [4+7²]=[4+49]=53. That gives us:
{300-4×53+32/4}-31=65.
Now we do the multiplication and division: 4×53=212 and 32/4=8:
{300-212+8}-31=65.
Now do {300-212+8}=96:
96-31=65, so the equation is true and the equation is correct.