Test lifecycle annotations

We have a class that performs mathematical actions:

class MathUtil {

    fun add(a: Int, b: Int): Int = a + b

    fun multiply(a: Int, b: Int): Int = a * b

    fun divide(a: Int, b: Int): Int = a / b
}

We wrote tests to check the performance of the class:

import org.junit.jupiter.api.AfterEach
import org.junit.jupiter.api.Assertions.*
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.TestInstance

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
internal class MathUtilTest {
    private var result = 5
    private val mathUtil = MathUtil()

    @AfterEach
    fun afterEach(){
        // required code  
    }

    @Test
    fun test_Add() {
        result = mathUtil.add(result, 5)
        println("test_Add(5,5) => $result")
        assertEquals(10, result)
    }

    @Test
    fun test_Multiply() {
        result = mathUtil.multiple(result, 5)
        println("test_Multiply(5,5) => $result")
        assertEquals(25, result)
    }

    @Test
    fun test_Divide() {
        result = mathUtil.divide(result, 5)
        println("test_Divide(5,5) => $result")
        assertEquals(1, result)
    }
}

An error was made when writing the test class, and the tests do not work.
The correct conclusion after passing the tests is:

test_Divide(5,5) => 1
test_Add(5,5) => 10
test_Multiply(5,5) => 25

Specify the missing code in the tests.