Răspuns:

3.a)20/3-21/9=20/3-(simplifici cu 3)7/3=13/3

b)21/5-27/15=21/5-9/5=13/5

c)30/7-36/42=30/7-6/7=24/7

d)41/6-35/30=41/6-7/6=34/6=17/3

e)31/8-15/40=31/8-3/8=28/8=7/2

f)25/9-28/63=25/9-4/9=21/9=7/3

4.a)35/8-20/32-3/8=35/8-5/8-3/8=27/8

b) 32/15-28/60-4/15=32/15-7/15-4/15=21/15=7/5

c) 41/18-7/18-39/54=34/18-13/18=21/18=7/6

d) 53/12-7/12-49/84=46/12-7/12=39/12=13/4

5.a)21/10-45/50-7/10=21/10-9/10-7/10=21/10-16/10=5/10=1/2

b) 35/24-19/24-30/72=35/24-19/24-10/24=35/24-29/24=6/24=1/4

c) 27/26-11/26-9/78=16/26-3/26=13/26=1/2

d) 37/30-19/30-16/60=18/30-16/60=18/30-8/30=10/30=1/3

Cu plăcere! (bara asta:/ înseamnă supra)