What should you do if the coefficients have the same sign?

Assuming this is a question about solving a set of equations.

If the coefficients of a variable are the same, the easiest way to solve it is to multiply one equation with -1, and then add that and the other equation together. Since the coefficients of a variable are now opposite, they will add to zero, thereby resulting in a single equation to solve.

Example:

[1] y+2x = 4

[2] -4y+2x = -6 |*(-1)

[2] 4y-2x = 6

[1] + [2] 5y+0 = 10

y = 2

2+2x = 4

x = 1

Solution: (1, 2)

Note: there is the usual way of solving any set of equations, (by substituting a variable for its expression), but in cases where you have the same or opposite coefficients of a variable, this method is the easier alternative.