第39页

信息发布者:
解:$\frac{7}{20}×19 + 35\%$
$=\frac{7}{20}×19+\frac{7}{20}×1$
$=\frac{7}{20}×(19 + 1)$
$=\frac{7}{20}×20$
$= 7$
解:$(\frac{5}{6}+\frac{3}{4}-\frac{1}{2})÷\frac{1}{24}$
$=(\frac{5}{6}+\frac{3}{4}-\frac{1}{2})×24$
$=\frac{5}{6}×24+\frac{3}{4}×24-\frac{1}{2}×24$
$=20 + 18-12$
$=26$
解:$\frac{2}{3}×\frac{17}{24}+\frac{17}{24}÷3$
$=\frac{2}{3}×\frac{17}{24}+\frac{17}{24}×\frac{1}{3}$
$=\frac{17}{24}×(\frac{2}{3}+\frac{1}{3})$
$=\frac{17}{24}$
解:$\frac{16}{11}-(\frac{1}{3}÷\frac{11}{15}+\frac{1}{5})$
$=\frac{16}{11}-(\frac{1}{3}×\frac{15}{11}+\frac{1}{5})$
$=\frac{16}{11}-\frac{5}{11}-\frac{1}{5}$
$=1-\frac{1}{5}$
$=\frac{4}{5}$
解:$19×(\frac{1}{19}+\frac{1}{31})×31$
$=19×\frac{1}{19}×31+19×\frac{1}{31}×31$
$=31 + 19$
$=50$
解:$\frac{8}{9}÷[(\frac{1}{2}+\frac{1}{6})÷\frac{3}{4}]$
$=\frac{8}{9}÷[\frac{2}{3}×\frac{4}{3}]$
$=\frac{8}{9}÷\frac{8}{9}$
$=1$
解:$3x + 2 = 9.8$
$3x=7.8$
$x = 2.6$
解:$1 - 85\%x = 0.15$
$85\%x = 0.85$
$x = 1$
解:$x - 85\%x = 0.15$
$15\%x = 0.15$
$x = 1$