Răspuns :

21.

raspuns:

explicatie pas cu pas:

fractii echivalente: a/b=c/d=>a x d=b x c

7/8(2=

22.

1/2(40=40/80

3/4(20=60/80

2/5(16=32/80

7/8(10=70/80

11/10(8=88/80

9/20(4=36/80