In my book it doesn’t say “If a number is even, then it is divisible by 20.” It says “If a number is divisible by 20, then it is even.”?
That is what a “converse” statement is. It swaps the hypothesis and conclusion. So, the solution provided already swapped them to show the converse that is being asked for.
This is true, if you multiply the number 20 by any number(we’ll use n as a variable), then any answer you end up with will be even.