Calculating casino payout and implementing function to simulate game

Suppose you're running a small casino and looking to introduce a new game. The game will use a simulated 10-sided die and the payout multiples will be as follows:

• Any roll with a value between 1 and 3 will return nothing
• Any roll with a value between 4 and 7 will return 1x the bet (e.g. if one bets $10 and rolls a 5, they'll simply get their money back)
• The multiple for 8 to 10 will need to be calculated, as specified below

As shown above, we're still looking to calculate what multiple we offer gamblers for a roll between 8 and 10. If we want to operate at an expected 25% profit margin, what payout multiple should we use? Once you've calculated the payout multiple, write a simple function that will simulate a large # of dice rolls and confirm your expected profit.