You need next code:
$A = $data['B'] - $_POST['C'] - 50; //for your first question
$A = $data['B'] - $_POST['C'] - ($data['B']*0.1); //for second question
solved Php Math Equation with variables [closed]
You need next code:
$A = $data['B'] - $_POST['C'] - 50; //for your first question
$A = $data['B'] - $_POST['C'] - ($data['B']*0.1); //for second question
solved Php Math Equation with variables [closed]