-3x + y = -14
x= -2y + 14
Which variable should an expression be substitute for?

9514 1404 393

  x

Step-by-step explanation:

There is already an expression given for x, so that is the easiest variable to substitute for.

Substituting for x using the second equation, you have ...

  -3(-2y+14) +y = -14

  6y -42 +y = -14

  7y = 28

  y = 4

  x = -2(4) +14 = 6

The solution is (x, y) = (6, 4).

Substitution for x is the easiest.

__

The first equation could be rearranged to give an expression for y:

  y = 3x -14

Then that can be used to substitute for y in the second equation. My lazy brain judges that to be more work.

x= cost per bracelet

number of bracelets * x + shipping charge = total cost

so

9x+9=72