The salesperson receives 5% of the sweater cost, that is, $40*5% = $2 per sweater. To find how many sweaters does he need to sell to make $100, we can use the next proportion.
[tex]\frac{2\text{ dollars}}{100\text{ dollars}}=\frac{1\text{ sweater}}{x\text{ sweaters}}[/tex]Solving for x,
[tex]\begin{gathered} 2\cdot x=1\cdot100 \\ x=\frac{100}{2} \\ x=50 \end{gathered}[/tex]He has to sell 50 sweaters
