Question

{495:[30:(6×4-9×a)]+339:3-124:4}-25×6=31

Answer 1

{495:[30:(24-9xa)]+113-31}-150=31
{495:[30:(24-9xa)]+113-31}=31+150
495:[30:(24-9xa)]+113-31=181
495:[30:(24-9xa)]+113=181+31
495:[30:(24-9xa)]+113=212
495:[30:(24-9xa)]=212-113
495:[30:(24-9xa)]=99
30:(24-9xa)=495:99
30:(24-9xa)=5
24-9xa=30:5
24-9xa=6
9xa=24-6
9xa=18
    a=18:9
    a=2