Question

)надо! решить уравнение с класс x- 1 5/7 = 2 1/7 и вот этот (12 5/13 +у ) -9 9/3 = 7 7/13

Answer 1

X- 1 5/7 = 2 1/7 
$1 \frac{5}{7} = \frac{7}{7} + \frac{5}{7} = \frac{7+5}{7} = \frac{12}{7}$
$2 \frac{1}{7} = \frac{2*7}{7} + \frac{1}{7} = \frac{14+1}{7} = \frac{15}{7}$

х-$\frac{12}{7} = \frac{15}{7}$

х=$\frac{12}{7} + \frac{15}{7}$

х=$\frac{27}{7}$=$3 \frac{6}{7}$

проверка
$3 \frac{6}{7} -1 \frac{5}{7} = \frac{27}{7} - \frac{12}{7} = \frac{15}{7} =2 \frac{1}{7}$ - верно

(12 5/13 +у ) -9 9/13 = 7 7/13
($\frac{161}{13}$+у)-$\frac{126}{13}$=$\frac{98}{13}$

$\frac{161}{13}$+у=$\frac{98}{13}$+$\frac{126}{13}$

$\frac{161}{13}$+у=$\frac{224}{13}$

у=$\frac{224}{13}$-$\frac{161}{13}$

у=$\frac{63}{13} =4 \frac{11}{13}$

проверка
$(12\frac{5}{13} +4 \frac{11}{13} )-9 \frac{9}{13} =( \frac{161}{13} + \frac{63}{13} )- \frac{126}{13} = \frac{224}{13} - \frac{126}{13}= \frac{98}{13} =7 \frac{7}{13}$ - верно

Answer 2

12/7+15/7=27/7, то есть 3 целых 6/7