Answer:
C. 81
Step-by-step explanation:
x^2-18x+81
(x-9)(x-9)
Answer:9.7536Step-by-step explanation:
Answer:
, 4.23 , 9/2
Step-by-step explanation:

9/2 = 4.5
4.23
Answer:
15x + 20y
Step-by-step explanation:
First, we need to combine like terms,
10x + 20y + 5x
15x + 20y
Since x and y are different variables, we cannot combine them, meaning that the answer is,
15x + 20y
Create a system of equations
x + y = 123
5x + y = 343
I use substitution
y = 123 - x
5x + 123 - x = 343
4x + 123 = 343
4x = 220
x = 55
Plug in
x + y = 123
55 + y = 123
y = 68
Check
5x + y = 343
5(55) + 68 = 343
275 + 68 = 343
343 = 343