Question 933109
delivery charges: cost {{{C=cost_per_mile+fixed_cost}}}

£{{{4.00}}} 

{{{60p}}}=£{{{0.60}}} per mile
 
for {{{x}}} miles  cost will be {{{0.60x}}}

equation: 
cost {{{C=0.60x+4.00}}}

if bob lives {{{12}}} miles away, means {{{x=12}}} 

{{{C=0.60*12+4.00}}}

{{{C=7.2+4.00}}}

{{{C=11.2}}} ->  jenny will charge £{{{11.2}}} to delivery the cakes