a. The total span of both bridges is 4.133 km.
When calculating the total of two different numbers, addition is the correct math operation to be used. We know that we need to add the length of the bridges together because the word <em>span</em> is the same as length. Also, the question asks about both bridges and uses the word <em>total. </em>2.063 + 2.07 = 4.133 km.
b. Leah and her dog will walk 4.126 km.
The question says that Leah walks across and back. This means she goes over the bridge two times. Times indicates that we should use multiplication for our math operation. Since she does the length two times, we need to multiply the length of the Walkway Over the Hudson bridge times 2. The math equation is 2.063 x 2 = 4.126 km.
<h3>Further Explanation</h3>
Addition
Addition is the math operation used to determine the total of a set of different numbers. Total means how many altogether.
Multiplication
Multiplication is the math operation used when finding the total when a number occurs multiple times.
Division
Division is used when breaking a number into an equal number of groups.
Subtraction
Subtraction is used when trying to find the difference between numbers
<h3>Answer Details</h3>
Subject: Math
Level: Middle School
Topic: Word Problems
<h3>Keywords</h3>
multiplication, division, addition, subtraction
<h3>Learn More</h3>
What is multiplication?: brainly.com/question/1135170
What are the properties of addition?: brainly.com/question/11036741
