The price of shirts in a store is $20 and the price of ties in the same store is $15. a customer buys 2 shirts and 3 ties during a sale when the price of shirts is discounted 15% and the price of ties is discounted 10%. how much did the customer save due to the sale?

First, find the new, discounted price of each item: 
20 x 0.15 = 3 < this represents the discount for the shirts, which are now $17.
15 x 0.10 = 1.5 < this represents the discount for the ties, which are now $13.50.

If he buys 2 shirts @ $17, that gives us $34. 3 ties @ $13.50 gives us $40.50.

$34 + $40.50 = $74.50 < this is the discounted total price.
$20 (2) + $15 (3) = $85 < this is the original price. 

Subtract the discounted price from the original: $85 - $74.50 = $10.50

The customer saved $10.50 due to sales.