1) 3/4 -1/1 +1/2 = 3/4 - 1 + 2/4 = 5/4 -1 = 1/4
2) 4/9 + 5/6 -3/4 = 16/36 +30/36 -27/36 =19/36
3) 4/15 -2/45 +7/9 = 12/45 -2/45 +35/45 = 1
4) 6/7 -1/4 +5/14 =24/28 -7/28 +10/28 = 27/28
5) 7/10 +9/14 - 3/35 = 49/70 +45/70 - 6/70 = 88/70 =1 18/70 = 1 9/35
6) 11/12 -1/9 +1/4 = 33/36 -4/36 + 9/36 = 38/36 =19/18 = 1 1/18
623 070÷63=9 890
ответ: 4 цифры
180а+684=30а+1134
180а-30а=1134-684
150а=450
а=3
1т2ц–700кг=1200кг–700кг=500кг=5ц