Answer:
He paid $2.35 for each pair of socks.
An equation using the variable S is
$77.99 = 9S + (3 × $8.28) + $32
Step-by-step explanation:
Let S be the cost of a pair of socks
From the question, Mark purchase nine pairs of socks, that is, the total cost of the pairs of socks is 9S
He purchase three packages of undershirts for $8.28 each; the total cost of the three packages of shirt will be 3 × $8.28 = $24.84
and he also purchase a pair of pants for $32
Since he spent a total of $77.99, we can write that
$77.99 = 9S + (3 × $8.28) + $32
Now, we can determine S, the cost of a pair of socks
$77.99 = 9S + (3 × $8.28) + $32
$77.99 = 9S + $24.84 + $32
$77.99 = 9S + $56.84
9S = $77.99 - $56.84
9S = $21.15
S = $21.15/9
S = $2.35
Hence, he paid $2.35 for each pair of socks.