You started by Debt to Assets 60%. get used to reason simply like that: for every 1$ of assets you have 0.6$ of debt (hence the 60% ratio). so Equity is 0.4$, because as you know debt + equity = assets.
You now have everything you need for any ratio: Debt = 0.6$ Equity = 0.4$ and Assets = 1$
So Equity/ Assets = 0.4/1=40%
Debt to Equity = 0.6/0.4=1.5
Leverage, which is Assets/Equity (know this) = 1/0.4 = 2.5
Practice again: Lets say Debt/Equity = 1.25
It means for every 1$ in equity you have 1.25$ of debt. So Assets = 2.25$ (debt + equity)
Now you can derive anythnig you want. Debt/assets = 1.25/2.25 = 0.55 or 55%
Assets/Equity = 2.25/1=2.25
with a bit of practice you will see how easy this is.