Answer: Maria has 10 bills of 5€ and 10 bills of 10€.
She has a total of 150€.
Step-by-step explanation:
Let be "f" the number of 5€ bills that Maria has and "t" the number of 10€ bills that Maria has.
Set up a system of equations:

Use the Substitution method to solve the system of equations:
1. Solve for "f" from the first equation:

2. Substitute the equation obtained into the second equation and solve for "t".
Then:

3. Substitute the value of "t" into the equation
and evaluate:

Therefore, Maria has 10 bills of 5€ and 10 bills of 10 €.
So the total amount of money she has, is:

She has a total of 150€.
Answer:
1. {5,-9}
2.{4}
3.{9/2}
Step-by-step explanation:
The equation
can be solved as follows:




Then, the solutions of the equation are
.
Now, if
, we can solve the equation
as follows:




So, the unique solution of this last equation is 
The last equation is
, where
. To solve this equation we can proceed as follows:







But, x=11/4 is not a solution of this equation. So the unique solution is x=9/2.
Answer:
Step-by-step explanation:

Answer:
Step-by-step explanation:
By 2 for the first one. And for 2 they skip counting by 6