D. \( f(x)=\left\{\begin{array}{ll}4.10+0.05747 x & \text { if } x \leq 1500 \\ 90.305+0.03788(x-1500) & \text { if } x>1500\end{array}\right. \) b) What is the monthly charge if 980 kWh are used? \( \$ \square \) (Type an integer or a decimal rounded to two decimal places as need

To find the monthly charge for 980 kWh, we need to determine which part of the function \( f(x) \) is applicable for \( x = 980 \) and then calculate the corresponding charge. Given function: \[ f(x) = \left\{\begin{array}{ll}4.10+0.05747x & \text{if } x \leq 1500 \\ 90.305+0.03788(x-1500) & \text{if } x > 1500\end{array}\right. \] Since \( 980 \leq 1500 \), we use the first part of the function: \[ f(x) = 4.10 + 0.05747x \] Now, we substitute \( x = 980 \) into the function to find the monthly charge: \[ f(980) = 4.10 + 0.05747 \times 980 \] Let's calculate the monthly charge. Calculate the value by following steps: - step0: Calculate: \(4.1+0.05747\times 980\) - step1: Multiply the numbers: \(4.1+56.3206\) - step2: Add the numbers: \(60.4206\) The monthly charge for 980 kWh is $60.42.