Calculator Cashback

Hello Hello, Today i create (again) User Interface Design based on what trending in Indonesia. yaps, promotion by e-wallets such as DANA Indonesia, Shopee, GoPay Indonesia, and OVO (PT Visionet Internasional). But, sometimes when use this payment method, i should calculate the discount to get maximal cashback from that purchase. once in a while the calculate little bit difficult because of many terms and condition. based on my problem experience, i trying to create design how we can get maximal cashback the name is CALCULATOR CASHBACK yeaaaaaaaaay hehehe :)