How to Assign true condition's value to a variable outside of if else condition in laravel?

I am trying to assign some value to a variable named $bonus in if else conditions and then I am trying to call $bonus outside of the if else condition so the true condition's variable should be called automatically. I have tried this code but it is giving me an error on debugging mode of laravel

Error:

 Undefined variable: bonus

Code:

   if($data->lend_amount >= 50 && $data->lend_amount <= 500)
                {
                    $bonus = ($data->lend_amount * 4)/100;

                }

                else if($data->lend_amount >= 500 && $data->lend_amount <= 50000)
                {
                    $bonus = ($data->lend_amount * 5)/100;

                }

   if ($user_b_update){
                        Transaction::create([
                            'user_id' => $data->user_id,
                            'trans_id' => rand(),
                            'time' => Carbon::now(),
                            'description' => 'Matching Bonus Of '.$bvp.' Users',
                            'amount' => $bonus,
                            'new_balance' => $newacc_bal,
                            'new_earning' => $newbal,
                            'type' => 4,
                            'charge' => 0
                        ]);