3. 15% x 3,5 : 1/4 = 15/100 x 35/10 : 1/4
= (3/20 x 7/2) : 1/4 = 21/40 x 4 = 84/40 = 2 4/40
= 2⅒
4. 1⅘ : 0,25 x 2⅕= 9/5 : 25/100 x 11/5
= 9/5 : 1/4 x 11/5 = 9/5 x 4 x 11/5 = 396/25
= 15 21/25
5. 0,75 x 0,2 : 2½ = 75/100 x 2/10 : 5/2
= 3/4 x 1/5 x 2/5 = 6/100