This should help: support.ptc.com/help/mathcad/r10.0/en/index.html#page/PTC_Mathcad_Help/example_solving_a_first_order_system_of_ODEs.html If not, and you have a specific problem, you should ask/show us on PTC Community where you can post screenshots and attach Mathcad files: community.ptc.com/t5/Mathcad/bd-p/PTCMathcad
