8/15· 7,5+( - 1/4 +1) 3,5 : 5/28 - (7/8 - 1 ) - 7,5 :одна целая7/8 - (-1+3/4) помогите...

1)
$1. \\ \frac{8}{15} \times \frac{75}{10} = 4 \times \frac{5}{5} = 4$
$2. \frac{ - 1}{4} + 1 = - \frac{1}{4 } + \frac{4}{4} = \frac{3}{4}$
$3)4 + \frac{3}{4} = 4 \frac{3}{4}$
2)3,5:5/28-(7/8-1)=19 целых 29/40

$\frac{7}{8} - 1 = \frac{7}{8} - \frac{8}{8} = - \frac{1}{8}$
$\frac{35}{10} \div \frac{5}{28} = \frac{35}{10} \times \frac{28}{5} = \frac{7}{5} \times 14 = \frac{98}{5} = 19 \frac{3}{5} =19.6$
$\frac{98}{5} = 19 \frac{3}{5} = 19.6$
$19 \frac{3}{5} - ( - \frac{1}{8}) = 19 \frac{24}{40} + \frac{5}{40} = 19 \frac{29}{40}$
3)7,5:1 7/8-(-1+3/4)=4 целых 1/4
$-1 + \frac{3}{4} = - \frac{4}{4} + \frac{3}{4} = - \frac{1}{4}$
$\frac{75}{10} \div \frac{15}{8} = \frac{75}{10} \times \frac{8}{15} = \frac{5}{5} \times 4 = \frac{20}{5} = 4$
20/5=4
$4 - ( - \frac{1}{4}) = 4 + \frac{1}{4} = 4 \frac{1}{4}$