Question

Question #b310b

Answer 1

`(x, y) = (x, x-90)`

Explanation:

Given two variables, at least two equations are needed to determine two unique values for those variables. With only a single equation, we are showing a relationship between the two variables which may be fulfilled by many `(x, y)` pairs.

In the given example, we have `x-y = 90`

`=> x - y + y - 90 = 90 + y - 90`

`=> y = x - 90`

Thus, for any `x` value, we can find a corresponding `y` value which fulfills `x-y=90` by setting `y=x-90`. If we graph this, we get a line, every point of which is an `(x, y)` pair satisfying our equation:

graph{x-90 [-275, 333, -168, 136]}

Example `(x,y)` pairs:
`(-10, -100)`
`(0, -90)`
`(1, -89)`
`(10, -80)`
`(90, 0)`
`(100, 10)`