18)
m aritm =(8+12,5):2=20,5:2=10,25
m geom = √(8*12,5)=√100=10
8<10<10,25<12,5
19.
(23,7+14,9)*7,5 :2=144,75dm²
20. (1/3)*(12/7)=4/7 kg
62,5% x=1,875
(62,5/100)*x=1,875
x=1,875:(62,5/100)
x=1,875:0,625= 1875: 625=3
21 ) -1+2-3+4.....-99+100-101=
=1+1...+1-101
avem 50 de 1 adunati pt ca avem 100 de numere de la 1 la 100 grupate cate 2, care insumate algebric dau , fiecare pereche, 1
50-101=-51
