The UNO board by itself uses something like 100mA.
The motors shouldn't be powered through the Arduino, and especially not through its voltage regulator. They should have a separate connection to the power supply or a separate power supply (with a common ground).
The motor voltage should "match".
**The motors will only "pull" the necessary current (**Ohm's Law) so the power supplies can be rated for more current.
You'll need separate power supplies for the 3V & 24V motors, or you'll need a good switchmode regulator that can supply 3V at about 4 Amps