A = 1/2 + 1/3 + 1/4 aducem la acelasi numitor amplificand fractiile cu numerele necesare:
A = 6/12 + 4/12 + 3/12
A = 13/12
B = 2/3 + 2/5 + 2/6 aducem la acelasi numitor amplificand fractiile cu numerele necesare:
B = 20/30 + 12/30 + 10/30
B = 42/30
A + B = 13/12 + 42/30
A + B = 65/60 + 84/60
A + B = 194/60
B - A = 42/30 - 13/12
B - A = 84/60 - 65/60
B - A = 19/60
A · B = 13/12 · 42/30
A · B = 13/6 · 21/30
A · B = 273/180
A : B = 13/12 : 42/30
A : B = 13/12 · 30/42
A : B = 13/2 · 5/42
A : B = 65/84
