s = standard version amount
h = high quality version amount
we know that there were 1090 downloads of the song, meaning s + h = 1090.
we also know that the total amount of MBs downloaded was 3353 MBs, and since the standard is 2.1 MBs and the high quality is 4.9MBs, then 2.1s + 4.9h = 3353.
![\begin{cases} s+h=1090\\ 2.1s + 4.9h = 3353\\[-0.5em] \hrulefill\\ h = 1090 - s \end{cases}\qquad \stackrel{\textit{substituting on the 2nd equation}}{2.1s+4.9(1090-s) = 3353} \\\\\\ 2.1s + 5341 - 4.9s = 3353\implies -2.8s + 5341 = 3353 \\\\\\ -2.8s=-1988\implies s = \cfrac{-1988}{-2.8}\implies \boxed{s = 710}](https://tex.z-dn.net/?f=%5Cbegin%7Bcases%7D%20s%2Bh%3D1090%5C%5C%202.1s%20%2B%204.9h%20%3D%203353%5C%5C%5B-0.5em%5D%20%5Chrulefill%5C%5C%20h%20%3D%201090%20-%20s%20%5Cend%7Bcases%7D%5Cqquad%20%5Cstackrel%7B%5Ctextit%7Bsubstituting%20on%20the%202nd%20equation%7D%7D%7B2.1s%2B4.9%281090-s%29%20%3D%203353%7D%20%5C%5C%5C%5C%5C%5C%202.1s%20%2B%205341%20-%204.9s%20%3D%203353%5Cimplies%20-2.8s%20%2B%205341%20%3D%203353%20%5C%5C%5C%5C%5C%5C%20-2.8s%3D-1988%5Cimplies%20s%20%3D%20%5Ccfrac%7B-1988%7D%7B-2.8%7D%5Cimplies%20%5Cboxed%7Bs%20%3D%20710%7D)
Let O be the intersection of the vertical line through ZX, and the horizontal line through YW.
The coordinates of this point are clearly (5, 2) as it is at the same x-coordinate as X and Z, and y-coordinate as Y and W.
So, YZO is a right triangle. By the Pythagorean theorem:
.
Since all sides of a rhombus are equal, then the perimeter is :
units.
Answer: third choice.
1st decimal place=tenth
2nd=hundreth
to round, you look at the place after it
so 13.8924439894 to tenth
look untill hundreth
13.89
if hundreth<u>></u>5, round tenth up
if hundreth place<5 leave tenth as is
13.89
9<u>></u>5
round up
8+1=9
13.9 is to theh tenth
Answer:
9
Step-by-step explanation:
7r+18=r²
r²-7r-18=0
factorizing
r²+2r-9r-18=0
r(r+2)-9(r+2=0
(r-9)(r+2)=0
r-9=0
r=9
check
(r²)=(9*9)=81
7r+18=7(9) + 8=81
