127.75
130+110+121+141+137+136 /6
=10228/6
=127.75
The total cost for this item is $18.19.
To find the sales tax of something, you move the decimal two places to the left on the percent. Then you multiply the items cost and the tax together, which gets you $1.19. Add the original amount with 1.19 and you get 18.19.
Note the binomial expansion,
(<em>a</em> + 1/<em>a</em>)³ = <em>a</em> ³ + 3<em>a</em> + 3/<em>a</em> + 1/<em>a</em> ³
so
<em>a</em> ³ + 1/<em>a</em> ³ = (<em>a</em> + 1/<em>a</em>)³ - 3 (<em>a</em> + 1/<em>a</em>)
Similarly,
(<em>a</em> + 1/<em>a</em>)² = <em>a</em> ² + 2 + 1/<em>a</em> ²
We're given <em>a</em> ² + 1/<em>a</em> ² = 79, so
(<em>a</em> + 1/<em>a</em>)² - 2 = 79
(<em>a</em> + 1/<em>a</em>)² = 81
<em>a</em> + 1/<em>a</em> = ±9
but <em>a</em> > 0, so we ignore the negative solution.
Then
<em>a</em> ³ + 1/<em>a</em> ³ = 9³ - 3×9 = 702
Answer:
-1 is your answer for this mate
