Consider the following two parallel irreversible first-order reactions, where k
1 = 2k
2 at 300 K. After complete conversion of R at 300 K, the concentration of P1 in the reaction mixture was 15 mol L
-1. The initial concentration of R (in mol L
-1) was

(k1 and k2 are the rate constants)
(rounded off to one decimal place)