£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
X + Y + Z = 8
2x = Z - 2
X + Z = 5
X = 1
1 + Y + Z = 8
Y + Z = 6
1 + Z = 5
Z = 4
1 + Y + 4 = 8
5 + Y = 8
Y = 3
The variables are 1, 3, 4.
Answer highlighted in blue. Hope this helps.