-6=-7+x
Make the variable to the left hand side and change it’s sign.
-6-x=-7
Move the constant to the right hand side and change its sign.
-x=-7+6
Calculate the sum
-x=-1
Change the signs of both sides of the equation .
X=1
Answer:

.
Step-by-step explanation:
5x + 3y = 26 (times 6) 30x + 18y = 156
6x + 7y = 21 (times 5) 30x + 35y = 105
.
30x + 18y = 156
<u>30x + 35y = 105 </u> <u> </u>
-17y = 51

y = -3
.
Substitute the value of y to one of equations
6x + 7y = 21
6x + 7(-3) = 21
6x - 21 = 21
6x = 21 + 21
6x = 42

x = 7
Convention in algebra is that we use letters such as a, b, c, etc., for parameters and letters such as x, y z, and so on, for variables.
Thus the parameters here are a, b and k. k is the constant of proportionality.
They didn’t use a ruler I think they made their own materials from what they had. Also thank you.
<u>Answer:</u>
5 hours was Aaron at the sitter
<u>Explanation:
</u>
Cost of baby sitting for the first hour: 10
Cost of baby sitting for additional hour= 12
Total cost of babysitting= 58
Since the cost of first hour is 10
Hence the remaining cost after first hour
= 54-10
=48
Which means 1 hour is consumed in the first hour
Now to calculate the remaining hours for every additional hour
= 
=4 hours
Hence the total hour Aaron was with the sitter
= 1 hour + 4 hours
= 5 hours