Question 1147822
<br>
Informally....<br>
The shipping cost is the same for both orders, so the additional 12-4=8 candles cost an extra $95-$35=$60; the price of each candle is $60/8 = $7.50.<br>
The cost of 4 candles is 4*$7.50 = $30, so the flat shipping cost is $35-$30 = $5.<br>
The cost of an order is $7.50 for each candle plus $5 for shipping:<br>
{{{C = 7.5x+5}}}<br>
Formal algebra does exactly the same thing, but using symbols instead of words.<br><pre>
let x be the number of candles; let a be the price per candle and b be the flat shipping cost.  Then

     12a + b = 95    [12 candles plus shipping costs $95]
      4a + b = 35    [4 candles plus shipping costs $35]
    --------------
      8a     = 60    [the difference between the two orders is 8 candles for $60]
       a     = 60/8 = 7.5    [the cost for each candle is $7.50]

     4(7.5) + b = 35    [the cost of 4 candles at $7.50 each, plus shipping, is $35]
     30 + b = 35    [the 4 candles cost $30]
     b = 35-30 = 5    [so the shipping cost is $5]<br></pre>