me assume that stuf shood be..... x^3 +(1/9)x^3 =25/36..... or (10/9)x^3=25/36.... so x^3=(9/10)*(25/36)=225/360 =0.625.... then, x=kube root(0.625)=0.854987973.... ######## me ges yu want x^3 +(1/27)x^3.... or (28/27)x^3.... =(28/27)*0.625.... =0.648148148148148... about 41/64 or 24/37