What you have is slope intercept form(best for graphing)
Ax+By=C and A must be positive
-1x+y = -8
so now A is negative so we multiply by another negative
1x-y = 8
The rest of the numbers can be negative and that is standard form.
Lit huh ? Should I get them
Since each unit cube I gives the value of oneI would multiply 48x1.Your answer would be 48