Jessica has $25 to buy 4 new pairs of socks
So the money she spends towards each pair of socks is [tex]\frac{25}{4}[/tex]
So each pair of socks would cost $6.25
Hence if the cost equation for x , where x is the number of socks
c(x) = 6.25x
the cost of one pair mulitplied by the number of pairs needed