Do what is in brackets first, then the multiplication.
First we'll substitute 
with 
Then we can separate this.
Then we'll solve this.
Then we'll plug in to find the extraneous solutions (if any)
Answer:
1+2, 1+4, 2+1, 2+3, 3+2, 3+4, 4+1, 4+3, 5+6, 5+8, 6+5, 6+7, 7+8, 7+6, 8+5, 8+7
Step-by-step explanation:
To be supplementary is to be equal to 180 degrees.
Equation for Kelli's earning = 20x + 100
Equation for Karl's earning = 25x + 50
Now, 20x +100 = 25x +50
25x-20x = 100-50
5x = 50
x = 10
So, your answer is 10 hours.
Hope this helps!
