x) -긇+(-);

ж) \(\frac{7}{15}\) + \(-\frac{3}{40}\) = \(\frac{7}{15}\) - \(\frac{3}{40}\) = \(\frac{7 \cdot 8}{15 \cdot 8}\) - \(\frac{3 \cdot 3}{40 \cdot 3}\) = \(\frac{56}{120}\) - \(\frac{9}{120}\) = \(\frac{56-9}{120}\) = \(\frac{47}{120}\)

Ответ: \(\frac{47}{120}\)