Answer:
67.52
Explanation:
So lets split it up.
First lets find the value of the dress when it is 20% off.
Then, lets find what it cost with 5.5% tax.
20% of a number is 1/5. We need to subtract 1/5 of 80 from 80. Or, in other words, we need to get 4/5 of 80.
So lets first divide 80 by 5, then multiply the 4.
Basically diving by the denominator, and multipling by the numerator. This is a useful trick when finding the fractional value of a number.
So:
80/5=16
A easy way to know what you get when dividing by 5s, is to take the number, multiply it by 2, then remove the 1s place.
As we can see: 2*80 is 160
Remove the ones place: 160 = 16
So we can see that 16 is our 20% of 80.
Remember, the question says we must remove 20% of the 80 dollars, so we must subtract 16 from 80:
80-16=64
So now we need to increase 64 by 5.5% to find the tax increase, and get our answer.
This is how I found my answer:
Put the 5,5% into decimal form - 0.055
Multiplied the 64 by the 0.055
5*64=320 - when multiplying by 5, we can divide the number by 2, then add a zero. This is the opposite of the dividing 5 trick,
64/2=32 + 0 = 320
Since theer is a 5 in the tenths place, and the hundreths. I just added this in twice:
3.20+0.320 = 3.52
This is 5.5% of 64.
Remember, we are increasing the price by 5.5%, so we are adding this to 64:
64+3.52=67.52
This is your answer.
Hope tihs helps!