AP ICET 18 Sep 2021 Shift 1 Paper

A student ' $\mathit{R}$ ' arrived to his class by $9.15\mathit{a}\mathit{m}$, and is late to the class by 40 minutes, but half an hour early to the arrival of another student ' $\mathit{Q}$ ' to the same class. If the student ' $\mathit{Q}$ ' is late to the class by ' $\mathit{x}$ ' minutes, then $\mathit{x}=$