Could anybody help me with these few they're awfully confusing to me.

6.(q^9)^2 a. 2q^18 b. q^18 c. q^81 d.q^11 7.(6q^6)^-4 a. 6q^1296 b. 1296q^2 c. 1/1296q^24 d. 6q^-24 8. what is the value of 12x^-3 y^-1 for x = -1 and y = 5? a. -12/5 b.-10 c.-0 d.5/12

Ican figure out 20 shares multiply by $117.98 =2359.6920 shares multiply by $124.32=2486.40then take 40 shares multiply by $128.48=5139.20after that i'm lost any be greatly appreciated.

Alex took his brother to a birthday party. the party was scheduled to last for 1 and 3/4 hours but they stayed for 4/5 of an hour more. how long did she stay at the party?