To determine the value of an expression for a given value of the variable we just need to plug the value of the variable in the expression and perform all the operations. In this case the expression is:
[tex]8x-6[/tex]and the value of x is -1, this means that we need to plug -1 in the expression; then we have:
[tex]8(-1)-6=-8-6=-14[/tex]Therefore, if x=-1 the value of the expression is -14