If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

Format for 'working together' problems:

(time together/time alone) + (time together/time alone) = 1 [whole job]

x/4 + x/6 = 1 Multiply by common denom (12) to clear the fractions:

3x + 2x = 12

Employees of a discount appliance store receive an additional 20% off of the lowest price on an item. If an employee purchases a dishwasher during a 15% off sale, how much will he pay if the dishwasher originally cost $450?

Full price = 100% Sale price = 100% - 15% = 85%

450 *.85 = ? [This is the sale price.]

Multiply the sale price by .80 to find the employee price.

Here's another way:

450 * .15 = sale discount 450 - sale discount = sale price.

Sale price * .20 = employee discount.

Sale price - employee discount = final price to employee.