Answer
Club = 7
Diamond = 6
Spade = 2
Heart = 5
Step-by-step explanation
Here it shows that 1 club + 1 diamond + 1 spade is equal to 15. Ok, let's get back to that one later.
In the next hint it shows that 3 clubs equals 21. So, in order to get the value of the club, divide 21 by 3, and you'll get 7. This means that 7 is the value of the club.
Now on to the third hint. Here it shows that 1 diamond plus 2 clubs are equal to 20. We already got the value of the club, which is 7, so add 7+7 and you'll get 14. Then, subtract 14 from 20 and you'll get the value of the diamond, which is 6.
Finally, the fourth hint. Here it shows that 1 diamond + 1 heart + 1 spade = 13. So, inorder to get the value of the heart, add the value of the diamond and the spade, which sums up to 8. Then subtract 8 from 13 and you'll get the value of the heart, which is 5.