Final answer:
By setting up an equation with the base salary as B and the commission as C, we find that the base salary is twice that of the commission. Therefore, the base salary accounts for more than half of the salesman's yearly income.
Step-by-step explanation:
To determine if the salesman's base salary was more than half of his yearly income, we can use the information provided: a 30 percent increase in commission would result in a 10 percent higher total income. Let's call the base salary B and the commission C. The total income is B + C, and if the commission were increased by 30 percent, the total income would be B + 1.3C.
A 10 percent increase in total income implies that B + 1.3C = 1.1(B + C). Simplifying this equation gives us 1.3C = 1.1B + 1.1C, which reduces to 0.2C = 0.1B, or 2C = B. This means the base salary is twice that of the commission, so the base salary indeed accounts for more than half of the salesman's yearly income.