Sally gets paid x dollars per hour for a 40-hour work week and y dollars for every hour she works over 40 hours. How much did Sally earn if she worked 48 hours?
Since she worked 48 hours, Sally will obtain paid her regular amount, x dollars, for 40 hours and a various amount, y, for the additional 8 hours. This becomes 40 times x plus 8 times y, that translates to 40x + 8y.