# -formulate-the-linear-equation-algebra-homework-help-

The idea of a large, stable middle class (defined as those with annual household incomes in 2010 between $39,000 and $118,000 for a family of three), is central to America’s sense of itself. But the U.S. middle class has been shrinking steadily from 61% of all adults in 1971

(*t* = 0) to 51% in 2011 (*t* = 4), where *t* is measured in decades. Research has shown that this decline is approximately linear. Find a linear function *f*(*t*) giving the percentage of middle-income adults in decade *t*, where t = 0 corresponds to 1971.