P=a*4
a=P/4
1) 12/4=3см
2) 8/4=2дм
3) 28/4=7дм
#657
первый пример:
1) 3 1/3+5 1/6==8 3/6=8 1/2
2) 1 1/2-2/5=1 1/10
3) 8 1/2×2/5=17/2×2/5=17/5=3 2/5
4) 2 3/4÷1 1/10=11/4×10/11=5/2=2 1/2
5) 3 2/5-2 1/2=2 7/5-2 1/2=9/10
второй пример:
1) 1/8+2/9=25/72
2) 25/72-1/4=7/72
3) 7/9-2/3=1/9
4) 1/9+1/6=5/18
5) 7/72×5 1/7=7/72×36/7=1/2
6) 1/2÷5/18=1/2×18/5=9/5=1 4/5
#658
1) 3/4÷(1/3х+1/4)+2/3=1
3/4÷(1/3х+1/4)=1-2/3
3/4÷(1/3х+1/4)=1/3
1/3х+1/4=3/4÷1/3
1/3х+1/4=3/4×3/1
1/3х+1/4=9/4
1/3х=9/4-1/4
1/3х=8/4
1/3х=2
х=2÷1/3
х=2×3=6
-----------------------------
3/4÷(1/3×6/1+1/4)+2/3=1
3/4÷(2+1/4)+2/3=1
3/4÷2 1/4+2/3=1
3/4×4/9+2/3=1
1/3+2/3=1
3/3=1
1=1
2) 5/6÷(1/4х-7/12)-1/2=3/14
5/6÷(1/4х-7/12)=3/14+1/2
5/6÷(1/4х-7/12)=10/14
5/6=10/14 ×(1/4х-7/12)
5/6=10/14×1/4х-10/14×7/12
5/6=5/28х-5/12
5/28х=5/6+5/12
5/28х=15/12
х=15/12÷5/28
х=15/12×28/5
х=7
--------------------------------
5/6÷(1/4×7/1-7/12)-1/2=3/14
5/6÷(7/4-7/12)-1/2=3/14
5/6÷14/12-1/2=3/14
5/6×12/14-1/2=3/14
5/7-1/2=3/14
3/14=3/14
3) 2 1/3÷(3/8х-5/6)+5 2/3=9 1/6
2 1/3÷(3/8х-5/6)=9 1/6-5 2/3
2 1/3÷(3/8х-5/6)=8 7/6-5 2/3
2 1/3÷(3/8х-5/6)=3 3/6
2 1/3÷(3/8х-5/6)=3 1/2
3/8х-5/6=2 1/3÷3 1/2
3/8х-5/6=7/3×2/7
3/8х=2/3+5/6
3/8х=9/6
х=9/6÷3/8
х=9/6×8/3
х=4
---------------------------------------
2 1/3÷(3/8×4/1-5/6)+5 2/3=9 1/6
7/3÷(3/2-5/6)+5 2/3=9 1/6
7/3×6/4+5 2/3=9 1/6
7/2+5 2/3=9 1/6
5 25/6=9 1/6
9 1/6=9 1/6
1)75*9=675(авт) всего 2) 1039-675=364(тр) всего 3)364:52=7(п) ответ: 7 троллейбусных парков
