Answer:
See below. 
Step-by-step explanation:
So, we know that Noah's purchase can be modeled by the equation: 

Part 1) 
The solution to the equation will be the value of x. 
In this case, x will represent the original price of the jeans. 
We know that Noah has a coupon for 10% off the <em>original price of the jeans</em>. 
So, 0.1x will represent how much of the original price Noah gets a a discount on. 
Therefore, (x - 0.1x) represents the total cost of the jeans <em>after</em> the coupon. 
So, x is our original price of the jeans. 
Part 2) 
To verify that 70 is <em>not</em> a solution, we can simply substitute 70 for x and check whether or not the equation is true. So: 

Multiply: 

Subtract: 

Add: 

However, we <em>can</em> verify that 60 <em>is</em> the solution by substituting. So, substitute 60 for every x: 

Multiply: 

Subtract: 

Add: 

So, 60 is indeed the solution and is the value of x. 
So, this means that $60 was the original price of the jeans.