Computer solutions for engineering problems of Umans, Stephen D. Máquinas Elétricas de Fitzgerald e Kingsley-7. AMGH Editora, 2014.
Simple problems has been solved with SMath Studio: https://en.smath.info/cloud/
Code and numerical problems has been solved with GNU Octave and Python 3 kernels in Jupyter Notebooks: http://jupyter.org/
Algebra problems has been solved with Symbolic Algebra System maxima: http://andrejv.github.io/wxmaxima/