Question

Choose the better definition of substitution.
A method for solving a system of linear equations. It is used to eliminate one of the variables by isolating one variable in one equation, and substituting the resulting expression for that variable in the other equation.
A pair of numbers used to locate a point on a coordinate plane; the first number tells how far to move horizontally and the second number tells how far to move vertically.
An expression constructed from a set of terms by multiplying each term by a constant and adding the results
Two or more linear equations with the same v

Answer 1

Seems like the first one to me :P

Answer 2

thanks