Let's solve
Using Pythagorean theorem
![\\ \sf\longmapsto H^2=P^2+B^2](https://tex.z-dn.net/?f=%5C%5C%20%5Csf%5Clongmapsto%20H%5E2%3DP%5E2%2BB%5E2)
![\\ \sf\longmapsto c^2=8^2+5^2](https://tex.z-dn.net/?f=%5C%5C%20%5Csf%5Clongmapsto%20c%5E2%3D8%5E2%2B5%5E2)
![\\ \sf\longmapsto c^2=64+25](https://tex.z-dn.net/?f=%5C%5C%20%5Csf%5Clongmapsto%20c%5E2%3D64%2B25)
![\\ \sf\longmapsto c^2=89](https://tex.z-dn.net/?f=%5C%5C%20%5Csf%5Clongmapsto%20c%5E2%3D89)
![\\ \sf\longmapsto c=\sqrt{89}](https://tex.z-dn.net/?f=%5C%5C%20%5Csf%5Clongmapsto%20c%3D%5Csqrt%7B89%7D)
![\\ \sf\longmapsto c\approx 9.22](https://tex.z-dn.net/?f=%5C%5C%20%5Csf%5Clongmapsto%20c%5Capprox%209.22)
Answer:
170
Step-by-step explanation:
Let the number of cell phones be x
2 : 3 = 68: x
Product of extremes = product of means
2 * x = 68 * 3
x = ![\frac{68*3}{2}](https://tex.z-dn.net/?f=%5Cfrac%7B68%2A3%7D%7B2%7D)
= 34 * 3
x = 102
Number of phones = 102 + 68 = 170
\begin{gathered}\{\begin{array}{ccc}3x+5y=2&|\cdot(-3)\\9x+11y=14\end{array}\\\underline{+\{\begin{array}{ccc}-9x-15y=-6\\9x+11y=14\end{array}}\ \ |\text{add both sides of equations}\\.\ \ \ \ \ -4y=8\ \ \ |:(=4)\\.\ \ \ \ \ y=-2\\\\\text{substitute the value of y to the first equation}\\\\3x+5\cdot(-2)=2\\3x-10=2\ \ \ |+10\\3x=12\ \ \ |:3\\x=4\\\\Answer:\ x=4;\ y=-2\to(4;\ -2)\end{gathered}
{
3x+5y=2
9x+11y=14
∣⋅(−3)
−9x−15y=−6
9x+11y=14
add both sides of equations
. −4y=8 ∣:(=4)
. y=−2
substitute the value of y to the first equation
3x+5⋅(−2)=2
3x−10=2 ∣+10
3x=12 ∣:3
x=4
Answer: x=4; y=−2→(4; −2)
The US postal service delivered 7.14 x 1010 pieces of mail in the month of December 7.14 x 1010=7211.4
3.21 x 1010 in the month of January. 3242.1
What is the total mail delivered for these two months?
7211.4
+ 3242.1
__________
10453 .5 TOTAL MAIL