Answer:
1 31/40 cups
Explanation:
Combine the fractions 7/8 c and 9/10 c:
Use the LCD 40, which is divisible by both 8 and 10.
Then we end up adding 35/40 c to 36/40 c, which yields 71/40 c.
You may either leave this result as is, or write the improper fraction 71/40 as a mixed number: 1 31/40 c.