A) 5/7a+3/14a при а =4целых2/3;7/13 б) 3/8y+y-1/4y при y = 2целых2/3;4/9

A)
$\frac{5}{7}a+ \frac{3}{14} a = ( \frac{5}{7} + \frac{3}{14} )*a = ( \frac{5*2 + 3}{14})*a= \frac{13}{14}a$

$a= 4 \frac{2}{3} \\ \\ \frac{13}{14} *4 \frac{2}{3} = \frac{13*14}{14*3} = \frac{13}{3} = 4 \frac{1}{3}$

$a= \frac{7}{13} \\ \\ \frac{13}{14} * \frac{7}{13} = \frac{1*1}{2*1} = \frac{1}{2}$

б)
$\frac{3}{8} y + y - \frac{1}{4} y = ( \frac{3}{8} +1 - \frac{2}{8} )y = 1 \frac{1}{8} y$

$y=2 \frac{2}{3} \\ \\ 1 \frac{1}{8}* 2 \frac{2}{3}= \frac{9}{8} * \frac{8}{3} =3$

$y= \frac{4}{9} \\ \\ 1 \frac{1}{8}* \frac{4}{9}= \frac{9}{8} * \frac{4}{9} = \frac{1}{2}$