Let's simplify the equation step by step.
You started with: \[ 40 + 20x = 100 - 10x \]
Then, you added \(10x\) to both sides: \[ 40 + 20x + 10x = 100 - 10x + 10x \]
This simplifies to: \[ 40 + 30x = 100 \]
Now, the equation we need to solve is: \[ 40 + 30x = 100 \]
Next, to isolate \(30x\), subtract 40 from both sides: \[ 30x = 100 - 40 \] \[ 30x = 60 \]
Now, divide both sides by 30 to solve for \(x\): \[ x = \frac{60}{30} \] \[ x = 2 \]
Now that we have confirmed that \(x = 2\), we need to find out the number of miles they both bike in 2 weeks to obtain the y-coordinate of the point of intersection.
For Harper: \[ y = 40 + 20(2) = 40 + 40 = 80 \]
For Audrina: \[ y = 100 - 10(2) = 100 - 20 = 80 \]
Both values confirm that after 2 weeks, they are both biking 80 miles.
Thus, the point of intersection is: \[ (2, 80) \]
So, you have correctly determined that the point of intersection is \( (2, 80) \).