At retirement, Keefer will have saved for 30 (that is, 70-40) years.
Monthly saving, P = $150, Annual rate of return, R = 4.5% = 0.045.
Therefore, future value (FV) at the time of retirement will be;
FV = P*[1+(R/12)^12*30]/(R/12)
Substituting all the parameters;
FV = 150*[1+(1+0.045/12)^360]/(0.045/12) = $113.907.92