Rewrite 7x + 4 = x – 2 as a system.

7x + 4 = x - 2 -- (1)

To rewrite the equation above as a system, we simply let (1) be equal to y, i.e.

7x + 4 = x - 2 = y -- (2)

Recall from the rule of transitivity: If a = b = c, then this implies that a = c & b = c. From this, we have (2) to be expressed as

y = 7x + 4 -- (i)
y = x - 2 -- (ii)

Note: (i) & (ii) are both regarded as a system of linear equation which can be evaluated simultaneously.