jamesk486 wrote:The price of a dress was first discounted by a certain percent and later by 25 percent of the discounted price. If these two discounts are equivalent to a single discount of 40% of the original price, what was the first discount?
A. 10%
B. 15%
C. 20%
D. 30%
E. 65%

jamesk486 wrote: The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour?

A. (20/5.280)(60^2/0.5)
B. (20/5.280)(60/0.5)
C.(20/5.280)(0.5/60^2)
D. (20)(5.280) / (60^2)(0.5)
E. (20)(5.280) / (60)(0.5)

jamesk486 wrote:The price of a dress was first discounted by a certain percent and later by 25 percent of the discounted price. If these two discounts are equivalent to a single discount of 40% of the original price, what was the first discount?
A. 10%
B. 15%
C. 20%
D. 30%
E. 65%

I have yet another method to this...
When you have two such percentages acting one after the other..

a + b + (ab/100) = Effective Percentage

a - 25 + a (-25/100) = -40
a - 25 - (a/4) = -40
3a = - 160 + 100
a = -20 => Discount of 20 percent