10. a) (n+83)/2=51,5
n+83=51,5*2
n+83=103
n=103-83
n=20
b) n+83=47,5*2
n+83=95
n=95-83
n=12
c) n+83=81,5*2
n+83=163
n=163-83
n=80
d) n+83=79,5*2
n+83=159
n=159-83
n=76
11. a) x=3^35:(3^3)^11=3^35:3^33=3^2=9
y=(2^13)^2:(2^4)^6=2^26:2^24=2^2=4
Ma=(9+4)/2=13/2
b) x=(2^12)^3:(2^3)^10=2^36:2^30=2^6=64
y=7^51:(7^2)^25=7^51:7^50=7^1=7
Ma=(64+7)/2=71/2
