What is a good example of a linear equation plz write an example

When using the linear combination metho e linear combination method to solve a system of linear equations, the four options are:

Determine domain and range, largest open interval, and intervals which function is continuous.

Astore sells 4 apples for $3 and 3 oranges for $4 if pete buys 12 apples and 12 oranges how much will it cost