Răspuns:
Folosim regula semnelor
+(-) = - și -(-) = +
[tex]\dfrac{2}{2} + \bigg( - \dfrac{7}{5}\bigg)- \bigg(- \dfrac{1}{15}\bigg) = [/tex]
[tex]= ^{15)}1 - \dfrac{^{3)} 7}{5} + \dfrac{1}{15} = \dfrac{15}{15} - \dfrac{21}{15} + \dfrac{1}{15} \\ [/tex]
[tex]= \dfrac{16}{15} - \dfrac{21}{15} = - \dfrac{21 - 16}{15} = - \dfrac{5}{15}^{(5} \\ [/tex]
[tex]= \bf - \dfrac{1}{3}[/tex]