Let's do that calculation part by part,

Due to maths operator precedence, we need to dive into deepest brackets, and after that, we have to calculate step by step

(18 == 2 * (18 / 10 + 18 % 10))

For (18 / 10 + 18 % 10)

18 / 10 -> 1

18 % 10 -> 8, Because it divides 18 by 10, the remainder is 8

8 + 1 = 9

After calculations: 18 == 2 * 9

2 * 9 -> 18

18 == 18 // true

So, that's very normal to be true