Do you want to solve this numerically or symbolically? The tag "ode45" sounds like a numerical solution, but it would be better if you mention this explicitely. What have you tried so far? What exactly is the problem?
Please read and consider https://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency. The term "urgent" discurages me and some others to post an answer.
