Question

2+3x[4+5x(6-x)]:7=8
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Answer 1

2+3x[4+5x(6-x)]:7=8
3x[4+5x(6-x)]:7=8-2
3x[4+5x(6-x)]:7=6
3x[4+5x(6-x)]=6×7
3x[4+5x(6-x)]=42
4+5x(6-x)=42:3
4+5x(6-x)=14
5x(6-x)=14-4
5x(6-x)=10
6-x=10:5
6-x=2
x=6-2
x=4

Answer 2

2 + 3 × [ 4 + 5 × ( 6 - x ) ] : 7 = 8

3 × [ 4 + 5 × ( 6 - x ) ] : 7  = 8 - 2

3 × [ 4 + 5 × ( 6 - x ) ] : 7 = 6

3 × [ 4 + 5 × ( 6 - x ) ]  = 6 × 7

3 × [ 4 + 5 × ( 6 - x ) ] = 42

4 + 5 × ( 6 - x ) = 42 : 3

4 + 5 × ( 6 - x ) = 14

5 × ( 6 - x ) = 14 - 4

5 × ( 6 - x ) = 10

6 - x = 10 : 5

6 - x = 2

x = 6 - 2

x = 4 → numarul necunoscut, aflat prin metoda mersului invers