Well you know that the total cost for the repair before any discount in both cases is $970. Company A has a 200 dollar discount so you can simply subtract 200 dollars from $970 to get $770. So you know company a will cost $770
With company B you know you are getting 15% off of the price of 970. This means to find how much you are getting off for company B you multiply 970 by 0.15 which ends up being 145.5 so company B is giving a discount of $145.50.
This means that the discount for company A is better because company A has $200 off compared to company B's $145.50