To solve problems like this one where you are asked to substitute numbers in for a variable, simply "plug" in the numbers where the variable is and find your result:
[tex] 2(5) - 2 = \boxed{8} [/tex]
[tex] 2(8) - 2 = \boxed{14} [/tex]
[tex] 2(14) - 2 = \boxed{26} [/tex]
