Đáp án:
Bài 7:
1, `(0,4x - 2) - (1,5x + 1) - (-4x - 0,8) = 3,6`
` 0,4x - 2 - 1,5x - 1 + 4x + 0,8 = 3,6`
` (0,4x - 1,5x + 4x) - (2 + 1 - 0,8) = 3,6`
` 2,9 x - 2,2 = 3,6`
` 2,9 x = 3,6 + 2,2`
` 2,9 x = 5,8`
` x = 5,8 : 2,9`
` x = 2`
2, `1/2x - 1/3 = 1/4x - 1/6`
` 1/2x - 1/4x = 1/3 - 1/6`
` x(1/2 - 1/4) = 2/6 - 1/6`
` 1/4 x = 1/6`
` x = 1/6 : 1/4`
` x = 2/3`