Пошаговое объяснение:

[tex]65(x + 1) + 75x = 310 \\ 65x + 65 + 75x = 310 \\ 140x + 65 = 310 \\ 140x = 310 - 65 \\ 140x = 245 \\ x = 245 \div 140 \\ x = \frac{7}{4} = 1 \frac{3}{4} = 1.75[/tex]