9873 - 9586 = 287 units used cost is 287 * 27.2 = 7806.4 p= 78.06 + standing charge of 12.40
total gas 80.46 Jayne's share 26.16 (because they have to pay part of a penny, so round up)
electricity
3542 - 3187 = 355 units used cost 355 * 7.1 2520.5 p = 25.21 + standing charge of 9.10
total electricity 34.31 Jayne's share 11.44 (because they have to pay part of a penny, so round up)
Rent * 3 months = 540 * 3 = 1620 Jayne's share 1620 / 3 = 540
total cost 3 months for Jayne
540 + 11.44 + 26.16+ 54 = 631 pounds 60 pence