With out subtracting 8.5-4.64 determine what digit will be in the hundreds place

Country carpets charges $22 per square yard for carpeting, and an additional installation fee of $100. city carpets charges $25 per square yard for the same carpeting, and an additional installation fee of $70

If myesha works overtime, she gets paid "time and a half" for every hour she works. in other words, for every hour over 40 hours myesha works each week, she gets her hourly pay plus half her hourly pay. what is myesha's pay per hour when she works overtime?

Pls! does anybody know a shortcut for answering these types of questions in the future?