Laravel Two request value get decrement and insert in column

Question

I'm New in Laravel I controller trying to get decrement (subtract) two input request value and pass result in ( balance_amount ) column.

example

input price request       100
input paid_amount request  50
result balance_amount      50

my Controller

 public function pay(Request $request)
    {
$request['price'] = $request->price;  //PRICE $150
$request['paid_amount'] = $request->paid_amount; //PAID $100
$request['balance_amount'] = $request->balance_amount; //BALANCE $50
 
    Installment::create($request);   
           }              

  return redirect( )->with('success',' PAID SUCCESSFULLY');

    }  

Answer 1

    public function pay(Request $request)
    {
        $validated = $request->validate([
            'price' => ['integer',],
            'paid_amount' => ['integer',],
        ]);

        Installment::create(
            [
                'price' => $validated->price,
                'paid_amount' => $validated->paid_amount,
                'balance_amount' => $validated->price - $validated->paid_amount,
            ]
        );

        return redirect()->with('success', ' PAID SUCCESSFULLY');
    }