There are several reasons the contract would be unenforceable. The main reason is that typos and obvious mistakes in a contract just result in the corrected contract applying.
Even if it were totally clear that both parties really intended 30% interest, which would not be the case, most US states have usury laws, 30% is way above the maximum allowed by any state. So the contract is automatically void in most states.
Even in states without usury laws, a mortgage at several times the prevailing rate would certainly be considered "unconscionable", making the contract unenforceable.
