Explanation:
Here's two ways you can solve, both involving addition but with fractions and with decimals.
With fractions, you can add 1/4 + 1/10 but you need a common denominator. In this case, the least common multiple between the two is 20, so multiply 1/4 by 5/5 and 1/10 by 2/2. Now, the fractions look like: 5/20 + 2/20 = 7/20, meaning she used 7/20 cups.
On the other hand, these fractions can be easily converted to decimals. 1/4 is 0.25 and 1/10 is 0.1. Add the two, and you get 0.35 cups.