A fuel quotient and a derived display

A fictional planning exercise gives 600 litres total fuel, of which 30 litres are explicitly defined as unusable. Two engines are assumed to consume 90 litres per hour each throughout the calculation. The exercise asks for a theoretical time based only on those stated quantities. It gives no taxi consumption, reserve requirement, route, wind, diversion or changing-power schedule. A separate display labeled FMS TOTAL is explicitly calculated by adding the same two tank-quantity indicators the learner is checking. A learner treats that total as an independent measurement confirming both indicators. The task is to calculate the limited quotient and explain the source relationship. No actual aircraft capacity, approved reserve or safe continuation decision is supplied, and no fuel-switching or balancing action should be inferred.