How to properly use array.prototype.filter() rather than .map()

Question

I have this object with values

const source = {
  \'10\': 3,
  \'15\': 3,
  \'20\': 2.5,
  \'25\': 2.5,
  \'30\': 2,
  \'35\': 2,
  \'40\': 2,
  \'45\': 2,