Tuấn Phong Lưu
1.(-2)^7 / 18^3 = -128/5832 = -16/729 2.(-7)^5 / 35^3 = -16807/42875 = -49/125 3.21^3 / (-7)^4 =63/2401 =27/7 4.3^4 / (-21)^3 = -81/9261 = -3/343