Bài 1:
a) B = 50% . 1$\frac{1}{3}$ . 20 . $\frac{7}{35}$ . 0,75
B = $\frac{1}{2}$ . $\frac{4}{3}$ . 20 . $\frac{1}{5}$ . $\frac{3}{4}$
B = $\frac{2}{3}$ . 20 . $\frac{1}{5}$ . $\frac{3}{4}$
B = $\frac{40}{3}$ . $\frac{1}{5}$ . $\frac{3}{4}$
B = $\frac{8}{3}$ . $\frac{3}{4}$
B = 2
Bài 2:
a) ($\frac{3}{4}$ . x + 2$\frac{1}{2}$) . $\frac{-2}{3}$ = $\frac{1}{8}$
$\frac{3}{4}$ . x + 2$\frac{1}{2}$ = $\frac{1}{8}$ : $\frac{-2}{3}$
$\frac{3}{4}$ . x + $\frac{5}{2}$ = $\frac{-3}{16}$
$\frac{3}{4}$ . x = $\frac{-3}{16}$ - $\frac{5}{2}$
$\frac{3}{4}$ . x = $\frac{-43}{16}$
x = $\frac{-43}{16}$ : $\frac{3}{4}$
x = $\frac{-43}{12}$
Vậy x = $\frac{-43}{12}$
b) $\frac{1}{3}$ . x - 0,5 . x = 0,75
($\frac{1}{3}$ - 0,5) . x = $\frac{3}{4}$
($\frac{1}{3}$ - $\frac{1}{2}$) . x = $\frac{3}{4}$
$\frac{-1}{6}$ . x = $\frac{3}{4}$
x = $\frac{3}{4}$ : ($\frac{-1}{6}$)
x = $\frac{-9}{2}$
Vậy x = $\frac{-9}{2}$
