Question about the goolge play balance I am playing clash of clans and I am trying buy premium item which is gem.

I am considering buying $30 google play store gift card.

And I am wondering if I can use google play balances to buy additional things in apps that are connected to google play.

If so, please tell me how to pay with them.
Yes you can


From Google help



  Redeemed gifts and some promo codes appear as part of your Google Play balance. This can be used for many purchases on Google Play



Types of content you can buy explains further, what you can buy and What you can't. And if the balance falls short 



  You usually can't combine your Google Play balance with other forms of payment to make a purchase. You can only combine it when the remaining Play Balance is less than the total order amount of your purchase. Then you can use the rest of your Play Balance and combine it with another form of payment (for example, credit/debit card, Wallet Balance, DCB, PayPal) to complete your purchase.