Answer:
15
Step-by-step explanation:
30 subtract 15 = 15 and both the 10 and the other 10 are the same
The answer is D. The +1 refers to the extra cup leftover from a previous bag. X represents how many cups are in each bag, and that is what you need to know. The three represents how many bags she bought, and the 25 represents how many cups of birdseed she had overall.
Hopefully this helps!
The answer is 25, 33. The difference between each consecutive number is 8.