И435 1,2И436 2,3 сестре нужнооо

№435
1) $\frac{1}{4}$ + y = $\frac{3}{7}$
y = $\frac{12}{28}$ - $\frac{7}{28}$
y = $\frac{5}{24}$

2) y - $\frac{5}{12}$ = $\frac{3}{10}$
y = $\frac{18}{60}$ + $\frac{25}{60}$
y = $\frac{53}{60}$
№436
2) $\frac{1}{5} + \frac{3}{8} - \frac{2}{9} = \frac{72}{360} + \frac{135}{360} - \frac{80}{360} = \frac{127}{360}$ = 0.375
3) $\frac{1}{4} + \frac{2}{9} - \frac{5}{36} = \frac{9}{36} + \frac{8}{36} - \frac{5}{36} = \frac{12}{36} = \frac{1}{3}$