The length of the bridge is the distance from the beginning to the end.
<em>The distance b between each beam is 9ft.</em>
Let:
<em />
<em> I-Beam</em>
<em />
<em> distance between I beam and the bridge</em>
<em />
<em> distance between each I beam</em>
<em />
Given that:


<em />
<em> --- length of the bridge</em>
<em />
From the diagram (see attachment), there are: 6 I-beams.
So, the length of the 6 I-beams is:




There are 2 I-beams beside the bridge
So, the distance between the 2 I-beams and the bridge is:



There are 5 spaces between the I-beams
So, the length of the total spaces is:


The total length is:

So, we have:

Collect like terms


Convert inches to feet



Divide both sides by 5

<em>Hence, the distance (b) between each beam is 9ft.</em>
Read more about lengths at:
brainly.com/question/22059747