4x=12+12
Find the value of x

What situation is an example of an observational study

Can any one me with the answers to these questions asap?

Which values of p and q result in an equation with exactly one solution? px-43=-42x+q choose all answers that apply: a) p=-43 and q=-43 b) p=42 and q=43 c) p=43 and q=−42 d) p=42 and q=42