Penny has jogged a total of 15 miles this week, which is 4 miles further than last week. How many miles (m) did she jog last week? 
 Choose the equation that correctly models this situation.
 1) 15m = 4m
 2) m + 4 = 15
 3) 15m + m = 4
 4) m divided by 4 = 15