Помогите пожалуйста 751 номер

1.
$\frac{52}{63} - \frac{x}{63} = \frac{25}{63} \\ \\ 52-x =25 \\ \\ x=52-25 \\ \\ x= 27 \\ \\ \frac{52}{63} - \frac{27}{63} = \frac{25}{63} \\ \\ \frac{25}{63} = \frac{25}{63}$
2.
$\frac{x}{38} + \frac{14}{38} = \frac{23}{38} \\ \\ x+14=23 \\ \\ x=23-14 \\ \\ x=9 \\ \\ \frac{9}{38} + \frac{14}{38} = \frac{23}{38} \\ \\ \frac{23}{38} = \frac{23}{38}$
3.
$( \frac{12}{13} +x)- \frac{5}{13} = \frac{9}{13} \\ \\ ( \frac{12}{13} +x)= \frac{9}{13}+\frac{5}{13} \\ \\ x= \frac{14}{13} - \frac{12}{13} \\ \\ x= \frac{2}{13} \\ \\ ( \frac{12}{13} + \frac{2}{13} )- \frac{5}{13} = \frac{9}{13} \\ \\ \frac{14-5}{13} = \frac{9}{13} \\ \\ \frac{9}{13} = \frac{9}{13}$
4.
$(x- \frac{21}{31} ) + \frac{14}{31} = \frac{25}{31} \\ \\ x- \frac{21}{31}= \frac{25-14}{31} \\ \\ x= \frac{11+21}{31} \\ \\ x= \frac{32}{31} = 1 \frac{1}{31} \\ \\ (1 \frac{1}{31} - \frac{21}{31} ) + \frac{14}{31} = \frac{25}{31} \\ \\ \frac{32-21+14}{31} =\frac{25}{31} \\ \\ \frac{25}{31} = \frac{25}{31}$