Question 1191411

if the price of kerosene is increased by $6 per litre, find the new price per litre if two-thirds of the new price is equal to five-sevenths of the old price
<pre>Let new price be N
Then old price = N - 6
Then we get: {{{matrix(2,3, (2/3)N, "=",  (5/7)(N - 6), 2N/3, "=", (5N - 30)/7)}}}
              7(2N) = 3(5N - 30) ----- Cross-multiplying
                14N = 15N - 90
          14N - 15N = - 90
                - N = - 90
    New price or {{{highlight_green(matrix(1,5, N, "=", (- 90)/(- 1), "=", "$90"))}}}
    That's IT!!</pre>