running wild

Select the set of equations that represents the following situation: The sum of two numbers is 36, and their difference is nine more than the smaller number. What are the two numbers?

Select the set of equations that represents the following situation: Mike invested $706 for one year. He invested part of it at 5% and the rest at 3%. At the end of the year he earned $28.00 in interest. How much did Mike invest at each rate of interest?

A university bookstore recently sold a wire-bound graph-paper notebook for $2.64, and a college-ruled notebook for $3.61. At the start of spring semester, a combination of 50 of these notebooks were sold for a total of $168.86. How many of each type were...