1. Write linear constraints with continuous and integer variables for the following problems. You need to clearly define the variables that you introduce and give an explanation of your constraints. (a) If we invest $100 or more on project 1, then we can only invest at most $100 on project 2. Suppose the investment amount on each project is a continuous variable. (b) If two continuous variables x1, *2 satisfy the linear constraint x1 + x2