The precision scientific instrument company

Astore sells two types of radios. one type sells $87 and the other for $119. if 25 were sold and the sales were $2495, how many of the $87 radios were sold a) 5 b) 20 c) 15 d)10

The table shown below gives the approximate enrollment at the university of michigan every fifty years. how many more students were enrolled at the university of michigan in 1950 than in 1900?

Jack has to solve the problem 281-266.how would you tell him to solve the problem ? tell which strategy you would use ,and solve the problem.