Tìm x: a) x x 1/2 + x x 3/4 = 6/7 b) 2/5 x x – 1/4 x x = 1/3 c) 5/6 x x = 4/5

`a) x × 1/2 + x × 3/4 = 6/7`

`=> x × (1/2 + 3/4) = 6/7`

`=> x × 5/4 = 6/7`

`=> x = 6/7 : 5/4`

`=> x = 24/35.`

`b) 2/5 × x – 1/4 × x = 1/3`

`=> x × (2/5 – 1/4) = 1/3`

`=> x × 3/20 = 1/3`

`=> x = 1/3 : 3/20`

`=> x = 20/9.`

`c) 5/6 × x = 4/5`

`x = 5/6 : 4/5`

`x = 25/24.`

`d) 12/17 : x = 1/2`

`=> x = 12/17 : 1/2`

`=> x = 24/17.`