option D
rent = 25b + 10
where b is hours for boat rented
85 = 25b + 10
25 b = 75
b = 75/25 = 3
First example:
Subtract the 8n on both sides to get the variable on one side of the equation. Do the same for the regular numbers. Then divide by -3.
![5n-14=8n+4\\ \\ 5n-8n=4+14 \\ \\ -3n=18\\ \\ n=-6](https://tex.z-dn.net/?f=5n-14%3D8n%2B4%5C%5C%20%5C%5C%205n-8n%3D4%2B14%20%5C%5C%20%5C%5C%20-3n%3D18%5C%5C%20%5C%5C%20n%3D-6)
This should be your final answer.
Second Example:
Do the same thing as explained in Example 1. Here's some work to help guide you.
![-15 - 5a + 4 = -2 + 30a + 26\\ \\ -5a-30a=-2+26+15\\ \\ -35a=39\\ \\ a = \frac{39}{-35}](https://tex.z-dn.net/?f=-15%20-%205a%20%2B%204%20%3D%20-2%20%2B%2030a%20%2B%2026%5C%5C%20%5C%5C%20-5a-30a%3D-2%2B26%2B15%5C%5C%20%5C%5C%20-35a%3D39%5C%5C%20%5C%5C%20a%20%3D%20%5Cfrac%7B39%7D%7B-35%7D)
That should be your final answer here.
Third Example:
![3 - 9x = -8x + 25\\ \\ -9x+8x=25-3\\ \\ -x=22\\ \\ x=-22](https://tex.z-dn.net/?f=3%20-%209x%20%3D%20-8x%20%2B%2025%5C%5C%20%5C%5C%20-9x%2B8x%3D25-3%5C%5C%20%5C%5C%20-x%3D22%5C%5C%20%5C%5C%20x%3D-22)
Hope this helps and its understandable! Let me know if you still don't understand.
Answer:
fourteen billion seven hundred ninety millio
The number is = 10x+y
if reverse the digits, the number is: 10y+x
The sum fo its digits is = x+y=5
I suggest this system of equations:
(10y+x)-(10x+y)=27 ⇒9y-9x=27
x+y=5
We can solve this system of equations by equaliztion method
x=5-y
9y-9(5-y)=27
9y-45+9y=27
18y=27+45
18y=72
y=72/18
y=4
x=5-y
x=5-4=1
The number is: 10x+y=10(1)+4=14
Answer: the number is 14