1.每日速算。
$2.5x + 3.7x =$
$7.5x - x =$
$4.5 × 0.4 =$
$7 ÷ 4 =$
$\frac{3}{4} + \frac{1}{6} =$
$\frac{7}{10} - \frac{1}{5} =$
$\frac{1}{5} + \frac{1}{6} =$
$\frac{7}{8} - \frac{5}{24} =$

1.$2.5x + 3.7x =6.2x$
$7.5x - x =6.5x$
$4.5 × 0.4 =1.8$
$7 ÷ 4 =\frac{7}{4}$
$\frac{3}{4} + \frac{1}{6} =\frac{11}{12}$
$\frac{7}{10} - \frac{1}{5} =\frac{1}{2}$
$\frac{1}{5} + \frac{1}{6} =\frac{11}{30}$
$\frac{7}{8} - \frac{5}{24} =\frac{2}{3}$

2.解方程。
$x - \frac{1}{9} = \frac{7}{8}$
$13×7 + 4x = 127$
$5.8x + 9.2x = 72$

$x = \frac{71}{72}$
$x = 9$
$x = 4.8$

3.大象和小象的体重各是多少吨？（用方程解答）

小象:0.7吨 大象:5.6吨