Explanation:
it all starts with having a good definition for a
a = 3x + 6
for the definition of b we need to transform the second equation
x = 1/3 b - 2 = b/3 - 2
3x = b - 6
3x + 6 = b
remember, if a = c and b = c, then it must be a = b.
that is the whole principle here. the symmetric property.
I am not sure what you must do here. so you select on the left the number of the step in the proof ?
if so, then
statement reason : number 1
a = 3x + 6 and 3x = b - 6 division : number 2
a = 3x + 6 and -b = -3x - 6 subtraction : number 3
a = 3x + 6 and b = 3x + 6 division : number 4
a = b = 3x + 6 symmetric : number 5
always remember, every change needed on one side of an equation we need to do on both sides, otherwise the equation is destroyed.
number 2 is "division" as division is a form of multiplication (and multiplication a form of division). we are multiplying by 3.
number 3 subtracts b and also 3x.
number 4 divides by -1.
and number 5 is the fished proof as mentioned above.