added function to check co-primes

maths/are_coprime.ts

@@ -0,0 +1,9 @@
+import { greatestCommonFactor } from "./greatest_common_factor"
+
+export const areCoprime = (a: number, b: number): boolean =>{
+
+    if(greatestCommonFactor([a,b]) === 1){
+        return true;
+    }
+    return false;
+}

maths/test/are_coprime.test.ts

@@ -0,0 +1,13 @@
+import { areCoprime } from "../are_coprime";
+
+describe('areCoprime', ()=> {
+    it('should return false when numbers are not coprime', () => {
+        const value = areCoprime(2,4)
+        expect(value).toBe(false)
+    })
+
+    it('should return true when numbers are  coprime', () => {
+        const value = areCoprime(2,3)
+        expect(value).toBe(true)
+    })
+})