:wave: the correct answer is r=9
heres my solution
T(r)=15Cr * (2x)^r * 3^(15-r)
T(15-r)= 15C(15-r) * (2x)^(15-r) * 3^r
T(r)/T(15-r)= (2x)^(2r-15) * 3^(15-2r) (nCk=nC(n-k))
therefore
2^(2r-15) * 3^(15-2r)=8/27
(3/2)^15 * (2/3)^2r=8/27
(2/3)^2r= (2/3)^3 * (2/3)^15...