Chapter 3 - Linear Systems - 3-2 Solving Systems Algebraically - Practice and Problem-Solving Exercises - Page 146: 11

c=-2 d=4

We are told that d equals 4. However, because the expression 3c+2d=2 has two variables in it, we must make it in terms of one variable by substituting out a variable. Thus, we substitute 4 in for d (because we know that d=4) to obtain that 3c+8=2. We solve to obtain that c equals -2.