diff --git a/src/index.js b/src/index.js
index ac593f4..5a8cc54 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,11 +1,59 @@
 // Entry
-class Entry {}
+class Entry {
+  constructor(date, amount, description) {
+    this.date = date;
+    this.amount = amount;
+    this.description = description;
+  }
+ getFormattedAmount() {
+  return this.amount + " €";
+}
+}
 
 // Income
-class Income {}
+class Income extends Entry {
+    constructor (date, amount, description) {
+        super(date, amount, description)
+        this.type = "income"
+    }
+}
 
 // Expense
-class Expense {}
+class Expense extends Entry {
+    constructor (date, amount, description, paid) {
+        super(date, amount, description)
+        this.paid = paid
+        this.type = "expense"
+    }
+    getFormattedAmount() {
+        return `-${this.amount} €`
+    }
+}
 
 // Budget
-class Budget {}
+class Budget {
+    constructor () {
+        this.entries = []
+    }
+
+    addEntry(entry) {
+        this.entries.push(entry);
+    }
+
+    getCurrentBalance() {
+        let total = 0 
+        for (let i = 0; i < this.entries.length; i++) {
+            let amounts = this.entries[i];
+
+            if (amounts.type === "income") {
+                total += amounts.amount;
+            } else if (amounts.type === "expense") {
+                total -= amounts.amount;
+
+            }
+        }
+        return total
+
+    }
+
+}