Given:
The total length of carriers A and B, T=4198 feet.
The difference in lengths of the carriers is, D=10 feet.
The length of football field, L=100 yards.
Let a be the length of carrier A and b be the length of carrier B. It is given that carrier A is longer than carrier B.
Hence, the expression for the difference in lengths of the carriers can be written as,

The total length of carriers A and B can be written as,

Add equations (1) and (2) to find the value of a.

We know, 1 yard=3 feet.
So, 1 feet=(1/3) yard
The length of carrier A in yards is,

We know, the length of a football field is l=100 yards
Now, the ratio between a and l can be found as

Hence, we can write

Since l is the length of a football field, the length of carrier A is about 7.0 football fields.