Alright! When you have a constant to a power times another constant to a power (ex. [x^3 times x^3] ) you simply add the powers and keep the base [x^6]. When you have a power to a power (ex. [(12^3)^3] ) you multiply the powers and keep the base [12^9]. When you have a constant to a power divided by a constant to a power (ex. [ x^2 divided by x^5] ) you subtract the powers and keep the base. It's hard to see the questions, so I'll leave this here for you to use as a guide.
40:28 are both divisible by 4. 40/4 is 10. 28/4 is 7. So the ratio would be 10:7 since neither is divisible by both the same number, this is the final ratio.
Just square the top and bottom of the fraction. 
and 
so we have 12/16 and then we reduce to 3/4