Two equations with infinite solutions would look the exact same. Example:
y=mx+b
y=mx+b
Example 2
y=2x+5
y=2x+5
For an equation with no solution they would have the same slope but different y intercepts. An equation with same slope and same y intercepts would have infinite solutions.
n+5=9 is the answer for this
4500 meters. You find this by adding 1/3 and 2/5 which equals 11/15. This means that the remaining 4/15 is 1200 meters long. Divide 1200 by 4 in order to find the distance per 1/15 and you get 300. Multiply 300 with 15 to get the total distance of the race.