The expression for the cost per person when five friends share the cost of a dinner equally is x/5. If the total cost is $30, each person's share of the cost would be $6.
When five friends share the cost of a dinner equally, the cost per person can be represented as the total cost of the dinner (x) divided by 5. Therefore, the expression for the cost per person is x/5.
If the total cost is $30, we substitute x with 30 in the expression we found earlier (x/5) and calculate the cost per person as follows:
30/5 = $6
Hence, the cost per person would be $6.