1. A shop sells two kinds of products $A$ and $B$. One day, a salesman sold both $A$ and $B$ at the same price $\$ 2100$ to a customer. Suppose product $A$ makes a profit of $20 \%$ but product $B$ makes a loss of $20 \%$. Then this deal
(A) make a profit of 870 ;
(B) make a loss of $\$ 70$;
(C) make a profit of 8175 ;
(D) make a loss of $\$ 175$;
(E) makes no profit or loss.
1. Answer: (D).
The original values are $2100 \div 120 \%=1750$ and $2100 \div 80 \%=2625$ respectively. Then the profit is
$$
1750+2625-2 \times 2100=-175 .
$$