Anna has more than 30 but less than 40 mochi balls. If she puts them equally into packets of 7, she would be short of 4 mochi balls. If she puts them equally into packets of 10, she would have 8 extra mochi balls. How many mochi balls does Anna have?
Multiples of 7: 21, 28, 35, 42, 49
Multiples of 7 (-4): 17, 24, 31, 38, 45
Multiples of 10: 20, 30, 40, 50
Multiples of 10 (+8): 28, 38, 48, 58
Common number more than 30 but less than 40: 38
Number of mochi balls that Anna has = 38
Answer(s): 38