G8.2 From 1 to 121 , there are $b$ numbers which are not divisible by 5 nor 7 . Find $b$.
Number of multiples of $5=24 \quad(120=5 \times 24)$
Number of multiples of $7=17 \quad(119=7 \times 17)$
Number of multiples of $35=3 \quad(105=35 \times 3)$
Number of multiples of 5 or $7=24+17-3=38$
Number which are not divisible by 5 nor $7=121-38=83$