We have the following:

A system of linear equations has infinite solutions when the graphs are exactly the same line.
for this to happen, on both sides the value of x must be equal:

replacing:
7.77/129.5 = 0.06
Therefore the tax rate is 6%
Answer:
57,600
Step-by-step explanation:
720 * 80 = 57,600
X=10
-3 on both sides
Then -6(x+4)+3 to the other side
The answer to the question is 2:3