Question 1206727


let's the original price of petrol be {{{p}}} and the the number of gallons purchased be {{{n}}}

if he paid full price, the number of gallons would be {{{n=180/p}}}...eq.1

if the price is reduced {{{10}}}%, the new price of petrol becomes {{{0.9p}}}, and the new number of gallons purchased becomes {{{n + 5}}}


so, with reduced price we have:

{{{180 = 0.9p * (n + 5)}}}...substitute {{{n}}}

{{{180 = 0.9p * (180/p + 5)}}}

{{{180 = 0.9p * ((180+5p)/p )}}}

{{{180 = 0.9* (180+5p)}}}

{{{180 = 4.5p + 162}}}

{{{4.5p =180- 162}}}

{{{4.5p =18}}}

{{{p=18/4.5}}}

{{{p=4}}}


answer:

the original price of petrol is ${{{4}}} per gallon