Ezekiel 44-46 is covenant renewal or reiteration of the law. 45:10-12 is a reiteration of the law of just measures. Verse 12 says:
The shekel shall be twenty gerahs; twenty shekels plus twenty-five shekels plus fifteen shekels shall be your mina.
What is the significance of the summation? Why not simply "one mina must be sixty shekels"?