Chemical Kinetics Part 2

Consider the following single step reaction in gas phase at constant temperature.
2A(g)+B(g)⟶C(g)
The initial rate of the reaction is recorded as r1 when the reaction starts with 1.5‌atm pressure of A and 0.7‌atm pressure of B. After some time, the rate r2 is recorded when the pressure of C becomes 0.5‌atm. The ratio r1:r2 is ______ ×10−1. (Nearest integer)