Grimecrior Lord of the Dead said:

How do you get 42 Galleons ?

https://prnt.sc/qjrc39

You can't.

The above number is not "how many galleons are there", but "how many galleons would you need to pick up that offer". That player has fully upgraded everything related to galleons, plus they have their level 10 prestige turned on, so they have 40 galleons for 88k res.

You probably don't have your prestige turned on, so your 40 galleons are worth 80k and, if you wanted to send 88k, you'd need 42 galleons, which is impossible. Turning on prestige level 10 will drop this number to 40 (if you have your galleons fully upgraded) and then you'd be able to take the offer.

Grimecrior Lord of the Dead said:

prestige is on , but i found issue . ty.

It is not just about prestige. Ultimately, it is about YOUR galleons' capacity vs. theirs. If you want more detail, please show me a screenshot of the "issue" (where you can see more than 40 galleons and  how much res they are asking for) and I'll elaborate.