Respuesta :
Answer:
Step-by-step explanation:
Given that there is a system of equations in two variables. When we have a single variable isolated in one of the two equations in a system, we can use substitution method.
So we substitute this variable in terms of other variable in the second equation so that we get now an equation in one variable. We can solve this by mathematical operations easily.
Hence correct answer is
C. substitute the expression equal to the solved variable into the other equation.