BMAT Ninja Problem Solving question

Hi! Can anyone help me with this?

It takes 1 hour 12 minutes to go from Chadwell Heath to Liverpool Street. The local MP has plans to increase connectivity in London by introducing a new railway. This will include a faster railway, with the speed increased by 20%, but will include three extra stops between Chadwell Heath and Liverpool Street. The time of the journey between Chadwell Heath and Liverpool Street is decreased by 10%. The bus fare accounts for the distance travelled, plus an additional 10p per additional stop. The initial bus fare is £1.50.
How much does the bus fare increase between Chadwell Heath and Liverpool Street?

The answer is B. £1.92 but I don’t understand how. I put A. £1.80 as the answer…