Add the number gotten from a db

I collected a data from a database and the data is base on o user id id, ie I select data from database table base on a user id. Now the selected result has some value (numbers) how do i check if that total sum of the number is equal to a certain amount. Am using Laravel 5.4 I query my db as follow

 $money = $DBTable::where('id', Auth::user()->id)->get();

now i have a column called cash how do i get the total sum of the cash column. what is the code for that since the result is an object do i do a foreach loop

 foreach ($money as $key => $value) {
    count($money->cash);
   }

this will return the number count of the value

 foreach ($money as $key => $value) {
 echo $earn->earned_amount + $earn->earned_amount;  
   }

this will add up individual value to themselves. so please can anyone tell me how it is done.

via dagogodboss