This is a system of two equations with two unknowns
[tex]\begin{gathered} A+B=2178 \\ A-B=14 \end{gathered}[/tex]Solve for A (or B) in one of the two equations and plug it into the other. For example,
[tex]\begin{gathered} A-B=14 \\ A=10+B \end{gathered}[/tex][tex]\begin{gathered} A+B=2178 \\ (10+B)+B=2178 \\ 10+2B=2178 \\ 2B=2178-14 \\ 2B=2164 \\ B=\frac{2164}{2} \\ B=1082 \\ \end{gathered}[/tex]Now,
[tex]\begin{gathered} A=10+B \\ A=10+1082 \\ A=1092 \end{gathered}[/tex]Carrier A = 1092 feet
Carrier B = 1082 feet