Let the youngest sister be n years
Lana will be 2n years, as her youngest sister is half her age
The age of the twins separately will be 2n-2 as they are 2 years younger than Lana
So, the equation looks like this:
n + 2n + 2(2n-2) = 45
Now solve for n:
3n + 4n - 4 = 45
7n - 4 = 45
7n = 49
n = 7
So the youngest sister is 7, Lana is 14 and the twins are 12. 14 + 12 + 12 + 7 =45
Answer:
Step-by-step explanation:
(6/5)√x = x - 6
(36/25)x = x² - 12x + 36
0 = x² - 13.44x + 36
x = (13.44 ± √(13.44² - 4(1)(36))) / (2(1))
x = (13.44 ± 6.052569702...) / 2
x = 3.69371... zebras
or
x = 9.74628... zebras
In either case we have some odd fractions of zebras hanging around. This makes me highly suspect that the question is misreported
S(8)=((100×(1−(50÷100)^(8))÷(1−50÷100)))
=199.22
