a) → amplifica cu 5 fractiile:
7/9 = ( 5×7) / (5×9) = 35/45
5/3 = (5×5)/ 5×3) =25/15
11/15 = ( 5×11) / (5×15) = 55/75
b) → cu 3
7/9 =(3×7) / ( 3×9) = 21/27
5/3 = (3×5) / ( 3×3)= 15/9
11/15 = (3×11) / ( 3×15) = 33/45
c) → 10
7/9 =(10×7) / (10×9)= 70/90
5/3=(10×5)/(10×3) = 50/30
11/15= (11× 10)/ (15×10) = 110/150
d) → 8
7/9 =(8×7) /(8×9)=56/72
5/3 = (8×5)/ (8×3) =40/24
11/15 = (8×11) / (8×15) = 88/120