1)1/3а-b при а=12, b=2/3

1/3*12-2/3=4-2/3=10/3=3целых 1/3

[latex] \frac{1}{3} 12- \frac{2}{3} = 3 \frac{1}{3} [/latex] [latex] \frac{1}{3} *12=4[/latex] 4*[latex] \frac{2}{3} =3 \frac{1}{3} [/latex]