<span>Testing for intelligence at multiple ages at one point in time is cross-sectional research. The goal of this type of research is to provide data on the whole population under study. This type of study is less costly than other forms of study.</span>
16+x=12
move 16 to the other side
sign changes from +16 to -16
so to get x by itself
16-16+x=12-16
x=12-16
x=-4
Answer: x=-4
The central plains region, Great Plains region, mountains & basins region and the coastal plains region
I got to go with d racial groups because they where singled out