I don't think giving you the exact answers would help, so here are the formulas:

For #1:
We're solving for a.
Answer:
Hey!
Try this!
Take the original price.
Divide the original price by 5.
Alternatively, divide the original price by 100 and multiply it by 20.
Subtract this new number from the original one.
The number you calculated is the discounted value.
Enjoy your savings!
I would think he answer would be c. Yoga
The answer to your problem is a+6x+5.