According to Psalm 90:10, how long are the days of our lives?

Answer: Seventy, or eighty if strong

"The length of our days is seventy years—or eighty if we are strong" (KJV: "threescore years and ten… fourscore").

“The length of our days is seventy years—or eighty if we are strong—yet their pride is but labor and sorrow, for they quickly pass, and we fly away.”— Psalm 90:10 (BSB)