Answer:
11). [tex](2 + 7x) + (11x + 6) = 80 \\ 18x + 8 = 80 \\ 18x = 72 \\ \boxed{x = 4}[/tex]
4 is the right answer.
12). [tex]13x + 52 = 22x - 2 \\ 9x = 54 \\ \boxed{x = 6}[/tex]
6 is the right answer.
13). [tex](14x + 4) + 24x = 118 \\ 38x = 114 \\ \boxed{x = 3}[/tex]
3 is the right answer.
14). [tex](x + 21) + (x + 23) = 68 \\ 2x + 44 = 68 \\ 2x = 24 \\ \boxed{x = 12}[/tex]
12 is the right answer.
