1 1/9+2,75+1/3;3,5+5 1/7-2 3/14;8,5+5/6-6,25;7,6-2/3+2 1/15; 2,25+11 1/15-7 1/6;6,8-2...

1
$1 \frac{1}{9}+2,75+ \frac{1}{3}= 1+2+\frac{1}{9}+0,75+ \frac{1}{3}=3+ \frac{1}{9}+ \frac{3}{4}+ \frac{1}{3}=\\ = 3+ \frac{4\cdot1+9\cdot3+3\cdot4\cdot1}{36}=3+ \frac{4+27+12}{36}=3+ \frac{43}{36}=3+1 \frac{7}{36}=4 \frac{7}{36};\\$
2.
$3,5+5\frac{1}{7}-2 \frac{3}{14}=3+5-2+ \frac{1}{2}+ \frac{1}{7}- \frac{3}{2\cdot7}=\\ =6+ \frac{7\cdot1+2\cdot1-3}{14}=6+ \frac{6}{14}=6 \frac{1}{7} ;$
3.
$8,5+ \frac{5}{6}-6,25=8-6+ \frac{1}{2}+ \frac{5}{6}- \frac{1}{4}=2+ \frac{6+10-3}{12}=2+ \frac{13}{12}=\\ =2+1 \frac{1}{13} =3 \frac{1}{3};\\$
4.
$7,6- \frac{2}{3}+2 \frac{1}{15}=7+2+ \frac{3}{5}- \frac{2}{3}+ \frac{1}{15}=9+ \frac{9-10+1}{15}=9;\\$
5.
$2,25+11 \frac{1}{15}-7 \frac{1}{6}=2+11-7+ \frac{3}{4}+ \frac{1}{15}- \frac{1}{6}=\\ =6+ \frac{45+4-10}{60}=6+ \frac{39}{60}=6 \frac{13}{20}$

6.
$6,8-2 \frac{1}{3}+1,2=6-2+1+ \frac{4}{5}- \frac{1}{3}+ \frac{1}{5} =6-2+1+1+ \frac{1}{3}=6 \frac{1}{3};$