Annual US Imports from China in the Years 1997-1999 Could Be

Multiple Choice

Annual U.S. imports from China in the years 1997-1999 could be approximated by $I = t ^ { 2 } + 3.5 t + 50 ( 2 \leq t \leq 4 )$ billion dollars per year, where t represents time in years since the start of 1995. During the same period, annual U.S. exports to China could be approximated by $E = 0.4 t ^ { 2 } - 1.6 t + 14 ( 2 \leq t \leq 4 )$ billion dollars per year.
Compute the area between the graphs of I and E over the interval $[ 2,4 ]$ . (Round your answer to the nearest $10 billion.)

A) $80 billion
B) $170 billion
C) $230 billion
D) $20 billion
E) $110 billion