`(3x)/2 = (5y)/4 = z/6`
`⇒ (3x)/2 = z/6` ; `(3x)/2 = (5y)/4` `(1)`
`⇒ 18x = 2z` ; `10y = 12x`
`⇒ 9x = z` ; `3y = 18/5x`
Khi đó: `2x - 3y + z = 13`
`⇒ 2x - 18/5x + 9x = 13`
`⇒ 37/5x = 13`
`⇒ x = 65/37`
Thay `x` vào `(1)` ta được:
`195/74 = z/6` ; `195/74 = (5y)/4`
`⇒ z = 585/37` ; `y = 78/37`
Vậy `x = 65/37` ; ` z = 585/37` ; `y = 78/37`