Well, basically what they are trying to do is isolate the y variable on the left side of the equation in order to get it in slope-intercept form (y=mx+b where "m" equals the slope and "b" is the y-intercept). So, in order to do this they have to do the inverse operations (so if it's adding they subtract, and if it's multiplying they divide.) Anyways, they do this with the intention of getting only the variable "y" on the left side of the equal sign. Once they did all that they got it in slope intercept form, and they know that the coefficient in front of the variable x is the slope.
The given equation is 
By solving the given equation, we get


While solving the equation,we get 0=0.
Therefore, the given equation is true for all the values of y.
Hence, we can say that the given equation has infinite number of solutions.
Answer:
yes because 3 is in - and it is less than 0
B. 18 feet,
Length to Width
5 : 3
30 : x
we have to find the number we multiply by 5 to get 30.
30/5 = 6
so we have to multiply both of the numbers (3 and 5 the numbers of the ratio) by 6.
3 x 6 = 18 ft
5 x 6 = 30 ft
therefore the answer is 18 ft