[tex]1) 3 \frac{1}{2} + x = 4 \\ x = 4 - 3 \frac{1}{2} \\ x = 3 \frac{2}{2} - 3 \ \frac{1}{2} \\ x = \frac{1}{2} [/tex]

[tex]2) \: x - \frac{3}{5} = \frac{2}{5} \\ x = \frac{2}{5} + \frac{3}{5 } \\ x = \frac{5}{5} \\ x = 1[/tex]

Надеюсь помогла