Найди значение b если -b =7/18·(1-5/14)

[latex]-b=\frac{7}{18}*(1-\frac{5}{14})[/latex] [latex]-b=\frac{7}{18}*\frac{14-5}{14}[/latex] [latex]-b=\frac{7}{18}*\frac{9}{14}[/latex] [latex]-b=\frac{7*9}{18*14}[/latex] [latex]-b=\frac{7*9}{9*2*7*2}[/latex] [latex]-b=\frac{1}{4}[/latex] [latex]b=-\frac{1}{4}=-0.25[/latex]