5 1 / 6 + 4 / 15t =- 2 / 5t -2 / 3
4/15t+2/5t=-2/3-5 1/6 4/15t+6/15t=-(4/6+5 1/6) 10/15t=-5 5/6 2/3t=-35/6 t=-35/6*3/2 t=-35/4 t=-8 3/4