Eva has more than 70 but less than 80 chocolate bars. If she puts them equally into packets of 9, she would be short of 7 chocolate bars. If she puts them equally into packets of 7, she would have 4 extra chocolate bars. How many chocolate bars does Eva have?
Multiples of 9: 54, 63, 72, 81
Multiples of 9 (-7): 47, 56, 65, 74
Multiples of 7: 56, 63, 70, 77, 84
Multiples of 7 (+4): 60, 67, 74, 81, 88
Common number more than 70 but less than 80: 74
Number of chocolate bars that Eva has = 74
Answer(s): 74