9(x + 3) + 15x
9x + 27 + 15x ...combine like terms
24x + 27 <==
Fern's estimate is not correct because he rounded 548 wrong, it would be rounded to 550 instead since the number 8 is closer to 10. So the correct answer would be 420.
You can use the distance formula to find the distance between any two points ion the plane. In this case, look carefully at the coordinates:
R(-1, 7) and T(-7, 7), Notice they both have y-coordinate 7. That means they are both on the same horizontal line. To find their distance, just subtract -7 from -1 and take the absolute value.
|-1 - (-7)| = |-1 + 7| = |6| = 6
The distance is 6 units
Assuming you're concerned with interest rate problems, r is generally involved in something like the formula ...
... i = prt
So, r will have the units of ...
... r = i/(pt) = (dollars)/(dollars·year) = 1/year
That is, r is <em>(some fraction) per year</em>.
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Often, the fraction is expressed as a percentage. The fraction will be unitless (as percentages are), leaving the units of r as year⁻¹.
