Explanation:
what ? you cannot do even simplest subtractions ?
what is it you don't understand here ?
how such a function works ?
you take every value for x (the input variable or argument), put it in place of the "x" (this is nothing else than a placeholder for the actual values) and then perform the mathematical operations. y is then the result of that.
x = 0
y = 0 - 7 = -7
the ordered pair of (x, y) is (0, -7)
x = 1
y = 1 - 7 = -6
(1, -6)
x = -3
y = -3 - 7 = -10
(-3, -10)
x = -5
y = -5 - 7 = -12
(-5, -12)