Which equation is in standard form?

3x+4y=103x+4y=10

19+3y=2x19+3y=2x

7y−7x=87y−7x=8

8+5x=3y

The american academy of pediatrics wants to conduct a survey of recently graduated family practitioners to assess why they did not choose pediatrics for their specialization. provide a definition of the population, suggest a sampling frame, and indicate the appropriate sampling unit.

If jobs arrive every 15 seconds on average, what is the probability of waiting more than 30 seconds?

Me find the answer and explain the process to find the answer of the problem appreciate it : )