數學問題(幾難下) [複製鏈接]

The sum of Peter and his brothers' age is 30.After 6 years,Peter's age is two- third of twice his brother's age.Find the present age of Peter.最好方程,只求色,不求答案

Let the present age of Peter be y
       the present age of his brother's age = 30 - y

          y + 6 = ( 30 - y +6 ) * 2 * 2/3
          y + 6 = 40 - 4/3y + 8
           7/3y = 42
                 y = 18

the present age of Peter is 18

應該係咁樣
p.s 應該係 two-thirds 你漏左個s