7.80=.05(66)+.1x
7.80=3.3+.1x
-3.3 -3.3
4.5=.1x
/.1 /.1
45 = x
45 dimes
Evaluate the function at the three values of the range and see what you get. The appropriate choice is ...
... D) {15, 3, 0}
_____
Evaluation can sometimes be simpler if you rearrange the function to a form called "Horner's form."
... f(x) = (x -4)x +3
Then the evaluation looks like (for x=-2) ...
... f(-2) = (-2-4)(-2)+3 = (-6)(-2) +3 = 12 +3 = 15
This is sufficient to identify D as the answer of choice.
Six thousand three hundred twenty four
Simple Interest Formula: A = P(1 + rt)
1555 = 1000(1+(0.05*t))
1.55 = 1 + (0.05*t)
0.55 = 0.05t
11 = t
The answer is 11. Whether that is 11 years or months or whatever depends on your exact question.