Assuming that you have the values for the year 2017, the break-even point would be 1500 units for the year 2017. To calculate this, we use the idea that at the breaking point, total sales is equal to the total cost or expenses made. Which would be:
selling (x) = fixed + variable (x)
x = fixed / (selling - variable)
x = 270000 / (600-420)
x = 1500 units