A hat salesman earns a commission of \( 30 \% \) of all hat sales made. Yesterday he sold 3 hats for \( \$ 90 \) each and 4 hats for \( \$ 50 \) each. How much did he earn in commission yesterday?

To calculate the commission earned by the hat salesman, we first need to determine the total sales amount from the hats sold. 1. **Calculate the total sales from the hats sold:** - For the 3 hats sold at \( \$ 90 \) each: \[ 3 \times 90 = 270 \] - For the 4 hats sold at \( \$ 50 \) each: \[ 4 \times 50 = 200 \] 2. **Add the total sales from both types of hats:** \[ 270 + 200 = 470 \] 3. **Calculate the commission earned:** The commission rate is \( 30\% \), which can be expressed as \( 0.30 \). Therefore, the commission is: \[ 0.30 \times 470 = 141 \] Thus, the hat salesman earned a commission of \( \boxed{141} \) dollars yesterday.