Question

Calcule o valor de x :

2/3 = 12/x
3/8 = x/40
x/20 = 2/5
100/x = 20/50
4/x = 1/4

Answer 1

2/3 = 12/x

2x = 3 * 12

2x = 36

x = 36 : 2

x = 18

.................

3/8 = x/40

8x = 40 * 3

8x = 120

x = 120/8

x = 15

.................

x/20 = 2/5

5x = 20 * 2

5x = 40

x = 40 : 5

x = 8

.................

100/x = 20/50

20x = 100 * 50

20x = 5000

x = 5000 : 20

x = 250

.................

4x = 1/4

x*1 = 4 * 4

x = 16

Answer 2

2/3 = 12/x

Multiplicar cruzado:

2x = 3 . 12
2x = 36
x = 36 / 2
x = 18

===
3/8 = x/40

Pode multiplicar cruzado:

8x = 40 . 3
8x = 120
x = 120 / 8
x = 15

===

x/20 = 2/5

Multiplica cruzado

5x = 20 . 2
5x = 40
x = 40 / 5
x = 8

===

100/x = 20/50

20x = 100 . 50
20x = 5000
x = 5000 / 20
x = 250

====

4x = 1/4

Multiplica cruzado

x.1 = 4 . 4
x = 16