Answer: 
Step-by-step explanation:
To solve this exercise you need to remember the following:
→ 
Therefore, keeping the above on mind, you can solve for x as following:


Remember that, by definition:
, then you have:

Subtract 6 from both sides of the equation.
Then the value of x is:

Answer:
13.31
Step-by-step explanation:
First do 35.19-12.78=22.41
I assume slightly more than $9 is .1
then subtract 22.41-9.1=13.31
Answer:
15 minutes i think
Step-by-step explanation:
45÷6=7.5
meaning 7.5 minutes per girl
so 4 girls would be 30 minutes of work
so 45-30=15