Question

Află valoarea necunoscutei din egalitatea: 27: [26+ (6 x 5-7xa):9] = 1.​

Answer 1

$\it 27:[26+(6\cdot5-7a):9]=1 \Rightarrow 26+(30-7a):9=27\bigg|_{-26}\Rightarrow \\ \\ \\ \Rightarrow (30-7a):9=1\bigg|_{\cdot9} \Rightarrow 30-7a=9\Rightarrow 7a=30-9\Rightarrow 7a=21\Rightarrow a=3$