In taking a physical inventory at the end of year 2017, Grant Company forgot to count certain

Question:

In taking a physical inventory at the end of year 2017, Grant Company forgot to count certain units. Explain how this error affects the following:
(a) 2017 cost of goods sold,
(b) 2017 gross profit,
(c) 2017 net income,
(d) 2018 net income,
(e) The combined two-year income,
(f) Income for years after 2018.