30% от 30% числа х равны 7,2. найдите число х.

Question

Математика: 30% от 30% числа х равны 7,2. найдите число х.

piloyanmurad · Accepted Answer

2/5b+2/3b-7/15b=2 1/2
6/15b+10/15b-7/15b=2 1/2
6/15b+3/15b=2 1/2
9/15b=5/2
3/5b=5/2
b=5/2 : 3/5
b=5/2 * 5/3
b=25/6
b=4 1/6

3 1/2 * (2/3x+4/7)=2 1/3
2/3x+4/7=7/3 : 7/2
2/3x+4/7=7/3 * 2/7
2/3x+4/7=2/3
2/3x=2/3-4/7
2/3x=14/21-12/21
2/3x=2/21
x=2/21 : 2/3
x=3/21
x=1/7

4 1/12 - 1 5/6x= 2 17/24
1 5/6x= 4 1/12 - 2 17/24
11/6x= 4 2/24 - 2 17/24
11/6x=3 26/24 - 2 17/24
11/6x= 1 9/24
x=33/24 : 11/6
x=3/4

3 1/3 : (3/7y - 13/15) = 1 9/16
3/7y - 13/15 = 3 1/3 : 1 9/16
3/7y - 13/15 = 10/3 : 25/16
3/7y - 13/15 = 10/3* 16/25
3/7y - 13/15 = 2/3 * 16/5
3/7y = 32/15 + 13/15
3/7y = 45/15
3/7y = 3
y = 3 : 3/7
y = 3 * 7/3
y = 7

MOGZ ответил