022 Exam 2 Sample B, Problem 8

Find the quantity that produces maximum profit, given demand function $p=70-3x$ and cost function  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle C = 120 - 30x + 2x^2.}