70. Create a pie chart for the number of people in three age groups of a tour group, where the central angle of the sector corresponding to the elderly is $9^{\circ}$ larger than that of the sector corresponding to children, the percentage of young adults in the total number of people is 5% higher than that of the elderly, and there are 9 more young adults than children. Then, the total number of people in this tour group is $\qquad$
Answer: 120
Solution: The percentage of the sector corresponding to a central angle of $9^{\circ}$ is $9 \div 360=2.5 \%$, so the percentage of young people plus the percentage of children $=5 \%+2.5 \%=7.5 \%$. Since there are 9 more young people than children,

the total number of people is
$$
9 \div 7.5 \% = 120 \text { (people). }
$$