Сколько будет 7/15 + ( 3/60 + 1/20 )

Question

Математика: Сколько будет 7/15 + ( 3/60 + 1/20 )

Rukishka05 · Accepted Answer

1) 2 1/3х + 2 5/12= 1 3/4 + 3 2/9х
2 1/3х - 3 2/9х= 1 3/4 - 2 5/12
2 3/9х - 3 2/9х = 1 9/12 - 2 5/12
-8/9х = - 8/12
-8/9х = - 2/3
х= -2/3 : (-8/9) = 3/4

2) 0,3(5х-7)=3(0,2х+3,2)
1,5х-2,1=0,6х+9,6
1,5х-0,6х=9,6+2,1
0,9х=11,7
х= 11,7:0,9=13

3) 4 1/6х + 11 1/4 * 4/15 = 2/3х + 5 2/3
4 1/6х + 3 = 2/3х + 5 2/3
4 1/6х - 2/3х = 5 2/3 -3
4 1/6х - 4/6х = 2 2/3
3 7/6х - 4/6х = 2 2/3
3 1/2х = 2 2/3
х= 2 2/3 : 3 1/2 = 8/3 : 7/2 = 16/21

4) 3(5-х)+13=4(3х-8)
15-3х+13=12х-32
-3х-12х= -32-15-13
-15х= -60
х= -60 : -15 = 4

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