"The tram leaves, and the frogs jump off the tram."
Translation:A villamos elindul, a békák pedig leugranak a villamosról.
If you have everything else according to the official translation, you would be putting the focus of the sentence on "pedig". Had, instead, you introduced the second part with "és", then you would be placing focus on the frogs, implying that it is frogs rather than some other animal that was jumping off the tram. The fact that the definite article is used, implies that the existence of the frogs is known to each of the conversationalists, so the focus, should there be any, should be on what they are doing.
I am having trouble understanding this explanation. I just ran into the same problem. So.....
A villamos elindul, a békák pedig ugranak le a villamosról.
...is saying that pedig is the focus and not békák due to the verb placement (with the prefix detached)? If I change ugranak le to leugranak....it shifts it back to békák?
Yes to your first question mark; in other words, don't split out the preverb if the verb follows "pedig", just as you don't split out the preverb if the verb follows "is".
No to your second question mark; it shifts the focus back to the verb itself, or else removes the focus altogether.