Simplify the expression 21b4 − 3b by combining like terms. choose the correct answer just tell me the answer i'm running out of time.
18b^3
21b^4 − 3b
18b^5
18b^4

Aresearcher believes increased perceived control influence the well-being of residents at a nursing home. to test this , she allowed one group of residents to have control over their daily lies, (where to eat etc) . the other group of 5 residents had these deceisions made by staff. the resident's feelings of well-being were measured on a 10 point scale at the end of a one month trial period. is there a difference on well-being?