Answer:
9
Step-by-step explanation:
9x2 is 18, so he can rent a bike for nine days if the rent is $2
X=18 (3/8)
(8x/7) +9 = 30
subtract 9 from both sides
8x/7=21
multiply 7 from both sides
8x=147
divide 8 from both sides and you get
x=18 (3/8)
The row echelon form of the matrix is presented as follows;

<h3>What is the row echelon form of a matrix?</h3>
The row echelon form of a matrix has the rows consisting entirely of zeros at the bottom, and the first entry of a row that is not entirely zero is a one.
The given matrix is presented as follows;

The conditions of a matrix in the row echelon form are as follows;
- There are row having nonzero entries above the zero rows.
- The first nonzero entry in a nonzero row is a one.
- The location of the leading one in a nonzero row is to the left of the leading one in the next lower rows.
Dividing Row 1 by -3 gives:

Multiplying Row 1 by 2 and subtracting the result from Row 2 gives;

Subtracting Row 1 from Row 3 gives;

Adding Row 2 to Row 3 gives;

Dividing Row 2 by -2, and Row 3 by 18 gives;

The above matrix is in the row echelon form
Learn more about the row echelon form here:
brainly.com/question/14721322
#SPJ1
Total cost = student cost + adult cost
t = 25s + 3(s+3)
t=28s+9