Use window frame specifications to compute moving averages
Monthly revenue is too noisy for the board — they want a smoothed trend line. Compute a 3-month trailing moving average alongside the raw monthly revenue. For each month, show year, month, monthly revenue, and the average of that month plus the two preceding months. The first two months will have fewer than 3 data points — that's fine, just average what's available.
Each hint you reveal reduces the XP you can earn. Try the query first.
Aggregate monthly revenue in a subquery first
Use AVG(monthly_revenue) OVER (ORDER BY year, month ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) for the 3-month trailing average
ROWS BETWEEN 2 PRECEDING AND CURRENT ROW = current month + 2 prior months = 3-month window