va rog frumos pana la ora 10:30 dau coroana fiecare pe rând si explicit

[tex]\it a)\ = 2\cdot9-3\cdot8+4\cdot7-5\cdot6=18-24+28-30=46-54=-8\\ \\ b)\ = (6-8)\cdot(10-12)=(-2)\cdot(-2)=4\\ \\ c)\ =\dfrac{\ 35^{(7}}{21}\cdot15^{-1}=\dfrac{5}{3}\cdot\dfrac{1}{15}=\dfrac{\ 5^{(5}}{45}=\dfrac{1}{9}[/tex]