Your expression is pure numeric but using mixed numbers.  A mixed number can be entered directly using Algebrator but the solver should express a mixed number as an addition.  So (49+1/2) and (27+1/3), otherwise "49 1/2" will be interpreted as "49 multiplied by 1/2", etc. 

To help you clearly understand our desktop software and how appropriate it may be for your needs, please use one of the following links to obtain a free trial of the program:

Windows: http://www.softmath.com/tr/alg51win-tr-en.exe

Mac: http://www.softmath.com/tr/alg51mac-tr-en.dmg

Finally, it is good to begin a solution with 'a few steps' and increase the number of steps as the additional details are helpful rather than confusing.  Press the 'Options' tab and control the number of steps and whether an answer should be an integer or a decimal number.  An integer answer is exact, a decimal number will typically be an approximate answer.