A company uses this formula to work out the cost, £A, of a taxi ride.

A = 5 + 1.9m + b

£5 is a fixed charge

m is the number of miles travelled

£b is a charge for booking online

a) Harry books a taxi online and travels 12 miles.

He pays £29.48 altogether.

How much is the charge for booking online?

b) If Sue books online and travels 20 miles, what will be