Question 1030417
a³c/ac⁴ X a³/ac⁴ 
The numerator is a^3*a^3= This is a*a*a* a*a*a=a^6.
The denominator is (ac^4)^2.  This is (a^1*c^4)^2.  You multiply the exponent of each inside by 2 to get a^2c^8.
a^6/a^2c^8=a^4/c^8
a^6/a^2=a*a*a*a*a*a/a*a, and two cancel.