20+(7 1/3 - 6 7/8):3/4 - (5 1/4 - 4 21/40): 1 9/20

Решите задачу:

$20+(7 \frac{1}{3}-6 \frac{7}{8} ): \frac{3}{4} -(5 \frac{1}{4}-4 \frac{21}{40} ):1 \frac{9}{20}=$

$20+(7\frac{40}{120} -6 \frac{105}{120} ): \frac{3}{4} -(5 \frac{30}{120} -4 \frac{63}{120} ): \frac{29}{20} =$

$20+ \frac{55*4}{120*3} - \frac{87*20}{120*29} =20+ \frac{55}{90}- \frac{3}{6}=20+ \frac{55}{90} - \frac{45}{90} =20+ \frac{10}{90}= 20 \frac{1}{9}$