How do I solve problems like this? I did it last year, but I don't remember how to do it. Solve for x:

1/2x + 3 = 7

2x + 3 - 4x - 7 = 11

thanks!!

Find two numbers if their sum is 91 and the ratio is 6: 7?

The birth weights of newborn babies in the unites states follow in a normal distrubution with a mean of 3.4 kg and standard deviation of 0.6 kg. reaserches interested in studying how. children gain weights decide to take random samples of 100 newborn babies and calculate the sample mean birth weights for each sample

The moats separating people from the animals are 5 m wide for lions and 4 m wide for the elephants. if the lion’s moat is 4 m deep, how deep should the elephants’ moat be?