Calculate Price Reduction: Finding New Price After $49.90 Discount

To solve this problem, we'll follow these steps:

• Step 1: Identify the given information

• Step 2: Apply the subtraction method to find the new price

• Step 3: Verify the solution matches one of the multiple-choice options

Now, let's work through each step:
Step 1: The problem gives us an original price of $\$99.9$ and a reduction of $\$49.9$.

Step 2: We use subtraction to find the new price:
$\text{New Price} = \text{Original Price} - \text{Reduction} = 99.9 - 49.9$

Aligning the decimal points and subtracting, we get:
$9$ in the hundredths place minus $9$ results in $0$, and $9$ in the tenths place minus $9$ is $0$, and finally, $9$ in the units position minus $4$ is $5$.

The calculation gives us:

$\text{New Price} = 50.0$

Step 3: Comparing with the choices, we find that the new price, $\$50$, corresponds to choice $3$: $\$50$ .

Therefore, the solution to the problem is:
$\$ 50$.