To find the total number of cups \( c \) that Kiara must sell to buy the snowboard, we can set up the equation based on the information given:
- Kiara has already sold 48 cups.
- She needs to sell 52 more cups.
This means that the total number of cups \( c \) that Kiara needs to sell is the sum of the cups she has already sold and the cups she still needs to sell:
\[ c = 48 + 52 \]
Now we can solve for \( c \):
\[ c = 100 \]
Therefore, the total number of cups Kiara must sell to buy the snowboard is 100 cups.