Answer: $180
Step-by-step explanation:
Given
Salesman earns 20% commission on merchandise he sells
Last month sales by him are $900
So, his commission out of $900
[tex]\Rightarrow 20\%\ \text{of}\ 900=0.2\times 900\\\Rightarrow \$180[/tex]
So, he grabbed $180 dollar as commissions