$A+B*C/D+E$
$\implies A+(B*C)/D+E$
$\implies A+(BC*\ /D)+E$
$\implies (A+BC*D/)+E$
$\implies (ABC*/D+\ +E) $
$\implies ABC*/D+E+$
another way to solve this just by using an operator stack, An operator occurs in expression(left to write scanning) push into the stack, when a high priority operator comes in the stack n low priority operator already exists then push it, when a high priority operator already in stack and low priority comes then first pop the high priority operator from stack n then push another operator which have low priority n so on... doing this we get option b.