Even integer: 2 x a, where a is a natural number without 0;
Odd integer : 2 x b + 1 , where b is a natural number;
So, 2 x a + 2 x b+ 1 = 2 x ( a + b ) + 1, which is an odd integer.
we are given
system of equations
First equation is

Second equation is

now, we can find augmented matrix

now, we can change it into reduced row echelon form
step-1: multiply the 1st row by 1/3

step-2:add -3 times the 1st row to the 2nd row

step-3:multiply the 2nd row by 1/4

step-4: add 2/3 times the 2nd row to the 1st row

so, we get

Answer is (5,-8)
4 hours for 18
7 hours for 25.50
Difference in hours: 7-4 = 3
Difference in cost: 25.50 - 18 = 7.50
7.50 / 3 = 2.50
A. They charge 2.50 per hour.
B. 2.50 x 4 = 10
18 - 10 = 8
The flat fee is 8 dollars
C. 8 + (2 x 2.50) = 13 dollars