I understand that say that multiplies the attacking stat but, can someone tell me an example?
They power up Electric and Dragon type moves by 50%
Transistor and Dragon's Maw both power up Dragon type or Electric type moves by 50%, or 1.5x.
Transistor powers up Electric type moves by 50%, while Dragon's Maw powers up Dragon type moves by 50%.
Sources: https://bulbapedia.bulbagarden.net/wiki/Transistor_(Ability) and https://bulbapedia.bulbagarden.net/wiki/Dragon's_Maw_(Ability)
Transistor and dragon's maw don't raise stats. They power up certain moves by 3/2 times.
For example, thunderbolt is an electric move with 90 base power.
If a Pokemon with transistor uses thunderbolt, then transistor activates because thunderbolt is an electric attack with a base power, and transistor multiplies thunderbolt's power by 3/2. The resulting power is 90 * 3 / 2 = 135.