I don't know how to create an matrix

(35%) A version of the "IS-LM" macroeconomic model by J.R. Hicks leads to the system of equations I(r) = S(Y) (1) aY + L(r) = Mi (2) where / is the investment function, S is the savings function, aY + L(r) is the demand for money, M; is the money supply, and a > 0 is constant. The endogenous variables are Y (income) and r (the interest rate), and their equilibrium values are denoted by Y"* and r*. Assume that I, S, and L are differentiable. (a) Totally differentiate equations (1) and (2). (b) Use your answer to (a) to solve for the equilibrium effects of money supply on the endogenous variables: Of*/OM; and Or*/OM