869)
a)
1) 3/4 + 1/6 = 9/12 + 2/12 = 11/12
2) 11/12 * 3 = 11/4 = 2 3/4
3) 5/6 - 1/2 = 5/6 - 3/6 = 2/6 = 1/3
4) 1/3 : 2/9 = 1/3 * 9/2 = 3/2= 1 1/2
5) 2 3/4 + 1 1/2 = 2 3/4 + 1 2/4 = 3 5/4 = 4 1/4
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б)
1) 1 1/5 + 2 3/10 = 1 2/10 + 2 3/10 = 3 5/10 = 3 1/2
2) 3 1/2 : 1/2 = 7/2 * 2 = 7
3) 6 3/4 - 2 2/3 = 6 9/12 - 2 8/12 = 4 1/12
4) 4 1/12 : 1 1/6 = 49/12 * 6/7 = 7/2 = 3 1/2
5) 7 + 3 1/2 = 10 1/2
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871)
a)
1) 3/5 + 1/4 = 0,6+0,25 = 0,85
2) 17 : 0,85 = 20
3) 7/8 - 1/4 = 7/8 - 2/8 = 5/8
4) (4/5)² = 4/5 * 4/5 = 16/25
5) 5/8 * 16/25 = 2/5 = 0,4
6) 20 + 0,4 = 20,4
б)
1) 5/8 + 5/6 = 15/24 + 20/24 = 35/24
2) 70 : 35/24 = 70 * 24/35 = 48
3) 3 1/9 - 1/3 = 3 1/9 - 3/9 = 2 7/9
4) (3/10)² = 3/10 * 3/10 = 9/100
5) 2 7/9 * 9/100 = 25/9 * 9/100 = 1/4
6) 48 + 1/4 = 48 + 0,25 = 48,25