1. 直接写出得数。(16☆)
$2.5×4=$
$1-\frac{9}{10}=$
$\frac{6}{7}-\frac{3}{7}=$
$\frac{1}{3}+\frac{1}{4}=$
$\frac{1}{5}-\frac{1}{6}=$
$1\frac{3}{8}+\frac{5}{8}=$
$\frac{1}{5}+\frac{1}{3}=$
$2-\frac{4}{5}=$
$\frac{3}{7}-\frac{3}{14}=$
$\frac{5}{8}+\frac{3}{8}=$
$\frac{1}{6}+\frac{2}{5}=$
$\frac{4}{27}+\frac{1}{9}=$
$\frac{1}{5}-\frac{1}{7}=$
$\frac{3}{8}+\frac{13}{8}=$
$\frac{1}{4}+1.75=$
$\frac{8}{3}-\frac{7}{4}=$
$\frac{1}{8}+\frac{5}{8}=$
$\frac{11}{12}-\frac{5}{12}=$
$\frac{5}{6}-\frac{1}{4}=$
$1-\frac{5}{6}+\frac{1}{6}=$
$\frac{2}{5}+\frac{3}{7}=$
$1-\frac{1}{4}=$
$1-\frac{4}{9}+\frac{5}{9}=$
$\frac{27}{25}-\frac{4}{13}-\frac{9}{13}=$
$\frac{1}{2}-\frac{1}{8}=$
$\frac{1}{6}+\frac{1}{4}=$
$\frac{2}{3}-\frac{2}{9}=$
$\frac{1}{2}+\frac{4}{5}-\frac{1}{2}+\frac{4}{5}=$
$\frac{2}{5}+\frac{3}{10}=$
$\frac{5}{8}+\frac{1}{4}=$
$\frac{14}{11}-\frac{7}{9}-\frac{2}{9}=$
$\frac{5}{6}+\frac{2}{5}-\frac{5}{6}+\frac{2}{5}=$

1. $2.5×4=10$
$1-\frac{9}{10}=\frac{1}{10}$
$\frac{6}{7}-\frac{3}{7}=\frac{3}{7}$
$\frac{1}{3}+\frac{1}{4}=\frac{7}{12}$
$\frac{1}{5}-\frac{1}{6}=\frac{1}{30}$
$1\frac{3}{8}+\frac{5}{8}=2$
$\frac{1}{5}+\frac{1}{3}=\frac{8}{15}$
$2-\frac{4}{5}=1\frac{1}{5}$
$\frac{3}{7}-\frac{3}{14}=\frac{3}{14}$
$\frac{5}{8}+\frac{3}{8}=1$
$\frac{1}{6}+\frac{2}{5}=\frac{17}{30}$
$\frac{4}{27}+\frac{1}{9}=\frac{7}{27}$
$\frac{1}{5}-\frac{1}{7}=\frac{2}{35}$
$\frac{3}{8}+\frac{13}{8}=2$
$\frac{1}{4}+1.75=2$
$\frac{8}{3}-\frac{7}{4}=\frac{11}{12}$
$\frac{1}{8}+\frac{5}{8}=\frac{3}{4}$
$\frac{11}{12}-\frac{5}{12}=\frac{1}{2}$
$\frac{5}{6}-\frac{1}{4}=\frac{7}{12}$
$1-\frac{5}{6}+\frac{1}{6}=\frac{1}{3}$
$\frac{2}{5}+\frac{3}{7}=\frac{29}{35}$
$1-\frac{1}{4}=\frac{3}{4}$
$1-\frac{4}{9}+\frac{5}{9}=\frac{10}{9}$
$\frac{27}{25}-\frac{4}{13}-\frac{9}{13}=\frac{2}{25}$
$\frac{1}{2}-\frac{1}{8}=\frac{3}{8}$
$\frac{1}{6}+\frac{1}{4}=\frac{5}{12}$
$\frac{2}{3}-\frac{2}{9}=\frac{4}{9}$
$\frac{1}{2}+\frac{4}{5}-\frac{1}{2}+\frac{4}{5}=\frac{8}{5}$
$\frac{2}{5}+\frac{3}{10}=\frac{7}{10}$
$\frac{5}{8}+\frac{1}{4}=\frac{7}{8}$
$\frac{14}{11}-\frac{7}{9}-\frac{2}{9}=\frac{3}{11}$
$\frac{5}{6}+\frac{2}{5}-\frac{5}{6}+\frac{2}{5}=\frac{4}{5}$

2. 找出下面每组数的最大公因数和最小公倍数。(8☆)
14 和 21
13 和 91
18 和 27
15 和 16

2. 14和21：最大公因数是7，最小公倍数是42
13和91：最大公因数是13，最小公倍数是91
18和27：最大公因数是9，最小公倍数是54
15和16：最大公因数是1，最小公倍数是240

3. 解方程。(24☆)
$8(x+2)=20$
$2.5x-0.5×8=6$
$x-\dfrac{1}{3}+\dfrac{1}{2}=\dfrac{7}{6}$
$5.6x÷2=2.1$
$x-0.6x=44.8$
$3x-\dfrac{1}{6}=\dfrac{5}{6}$

3. $8(x+2)=20$ $x=\frac{1}{2}$
$2.5x-0.5×8=6$ $x=4$
$x-\dfrac{1}{3}+\dfrac{1}{2}=\dfrac{7}{6}$ $x=1$
$5.6x÷2=2.1$ $x=0.75$
$x-0.6x=44.8$ $x=112$
$3x-\dfrac{1}{6}=\dfrac{5}{6}$ $x=\frac{1}{3}$