Megan's cousin wants to buy a new sound system for his car. she goes to the electronics store to him to pick it out. the base system costs $395. adding a subwoofer is an additional $89. two extra rear speakers are $75 each. and upgrading to a six-cd disk changer is an additional $225. round each amount to the nearest hundred dollars to find a reasonable estimate for the total cost of the new sound system. a. $600 b. $650 c. $700 d. $900