To calculate the total amount Roy will pay back, we first need to find the amount of interest he will be charged.
The formula for simple interest is:
[tex]\[ \text{Interest} = \text{Principal} \times \text{Rate} \times \text{Time} \]\[ \text{Interest} = \text{Principal} \times \text{Rate} \times \text{Time} \][/tex]
Given:
- Principal (P) = $150
- Rate (R) = 4% or 0.04 (as a decimal)
- Time (T) = 1 year
Substitute these values into the formula:
[tex]\[ \text{Interest} = 150 \times 0.04 \times 1 \]\[ \text{Interest} = 6 \][/tex]
So, Roy will pay $6 in interest.
To find the total amount Roy will pay back, we add the interest to the principal:
[tex]\[ \text{Total amount} = \text{Principal} + \text{Interest} \]\[ \text{Total amount} = 150 + 6 \]\[ \text{Total amount} = 156 \][/tex]
Therefore, Roy will pay a total of $156.
So, the correct answer is B. $156.