Question

X + 1/5 = 1 ; 1 - X = 3/8 ; a/11 + 4/11 = 1

Answer 1

X=1-1/5
X= 5/5 - 1/5
X = 4/5

Answer 2

$x + \frac{1}{5} = 1 \: \: \: \: \\ x = 1 - \frac{1}{5} \\ x = \frac{4}{5}$
.............

$1 - x = \frac{3}{8} \\ - x = \frac{3}{8} - 1 \\ - x = \frac{3}{8 } - \frac{8}{8} \\ - x = - \frac{5}{8} \\ x = \frac{5}{8}$
.............

$\frac{a}{11} + \frac{4}{11} = 1 \\ \frac{a}{11} = 1 - \frac{4}{11} \\ \frac{a}{11} = \frac{7}{11} \\ 11a = 77 \\ a = 7$