Math Problem Solver

Let 𝑑 be the difference between the largest and smallest values ​​possible to be reached by the expression 7𝑦 + (𝑥 − 𝑦)/7, where 𝑥 and 𝑦 are non-negative real numbers such that 𝑥 ≤ (7 − 𝑦)^3. Calculate 𝑑.