How do you use the substitution method

What are “like terms”? why can we only add like terms?

Which statement about the relative areas of δabc and δxyz is true? the area of δabc > the area of δxyz the area of δabc < the area of δxyz the area of δabc = the area of δxyz more information is needed to compare.

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