The answer is x=5/8. The reason for this is when you divide it equal 0.625 then when you multiply that by 2 it equals 1.25. After you do that you add 5 which is 6.25. Now we divide 4/5 which is 0.8. Now, we multiply 6.25x0.8=5. 5-4=1. Therefore your answer is 5/8. Hope this helps :)
Try 135. I’m not foresee!
£110 as 45mins times 4 radiators divided by 60 mins =3 hours
3 hours + 1 hour = 4 hours
4 hours times £20= £80
£80+£30=£110
Correct answer is the one you put