Question

If f(x) = −2 + 8, what is f(−1.8)?

Answer 1

As the question is written,
.. f(-1.8) = -2 +8 = 6

We suspect x is missing. Perhaps you intend
.. f(x) = -2x +8
.. f(-1.8) = -2(-1.8) +8 = 11.6