The exercise asks for a linear equation to be solved, where the variable is randomized. There's a line of PG code like this:
$x = list_random( 'a' .. 'n', 'p' .. 'z', 'A' .. 'N', .. 'P' .. 'T', 'V' .. 'Z' );
# 'o', 'O' skipped as they look like '0'; 'U' skipped because PG defaults to seeing it as the union operator
The answer is supposed to be entered like
x = 7
Students may default to typing something like "7".
So all that motivates:
Enter your solution in the form <c><var name="$x"/> = number</c>.
I think you might suggest:
Enter your solution in the form <c>variable = number</c>.
which is a fallback plan if I don't end up with a way to use c/var.