Question 127958
A householder can choose to pay for his electricity by one of the following methods:
i) a basic charge of £6.50 plus a charge of £0.50 per unit
ii) a basic charge of £8.50 plus a charge of £0.48 per unit
Find the number of units for which the bills will be the same.

taking y=total charge and  x number of units
i) y=6.5+0.5x
ii)y=8.5+0.48x

so 6.5+0.5x=8.5+0.48x
then  -2+0.02x=0
then   0.02x=2
then   x=2/0.02=100

R: 100 units