Can someone else explain it but more easier for an 8th grader

Question

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In January, gasoline cost $1.05 per gallon. In July, gasoline cost $1.20 per gallon. Find the percent of increase.

Would the answer for this question be 14.3?

And how do you do percent of decrease?
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The original cost of a computer is $900. If the price is decreased by 15%, what is the sale price?

I need help with this question(:
Thank you

Answer 1

1.20 - 1.05 = 0.15
0.15 / 1.05 = 0.143 = 14% decrease

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900 * 0.15 = 135
900 - 135 = 765

Answer 2

Kenya -- we have students posting upper level high school and college math. After this I suggest you use 8th grade math as your subject.

Answer 3

oh ok