Abicycle costs $120. you must pay an 8% sales tax rate. explain how to use mental math to find the amount of tax on the bicycle?

I really had to do mental math this would be my thought process

$100, eight percent of if would be 8 dollars

Then I'll figure out how much is ten percent of $10 which is $0.8 and add 0.8 + 0.8 together to get 8 percent of $20

Then I'll add it all together

8 + 1.6 = 9.6

120 + 9.6 = $129.6

If you can do this mentally then do this equation below

120 x 1.08 = $129.6  

step-by-step explanation:

if you want to solve percent error follow these steps.

1. subtract the accepted value from the experimental value.

2. take the absolute value of step 1.

3. divide that answer by the accepted value.

4. multiply that answer by 100 and add the % symbol to express the answer as a percentage.

if you want to solve percent of change just do this.

1. work out the difference (increase) between the two numbers you are comparing.

2. divide the increase by the original number and multiply the answer by 100. if your answer is a negative number then this is a percentage decrease.

hope this : )

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step-by-step explanation: