In 1994 world aquaculture was about 20.8 million metric tons.

In 2000 world aquaculture was about 35.5 million metric tons.

this means that in 2000 - 1994 = 6 years the change of the agriculture is 35.5 - 20.8 = 14.7 million metric tones aquaculture

the rate r = 14.7 / 6 = 2.45 million metric tones aquaculture per year

a) Write an equation that gives world aquaculture (in million metric tons) as a function of a number of years since 1991

in the year 1991 the aqua culture was 20.8 - r*3 = 20.8 - 2.45*3 = 13.45 million metric tones aquaculture

f(0) = 13.45

f(t) = f(0) + t*r

f(t) = 13.45 + 2.45*t, where t is the number of years since 1991.

b)in 2001 China was responsible for 70.2% of world aquaculture. Approximate Chin's aquaculture in 2001

for the year 2001, t = 2001 - 1991 = 10 years

f(10) = 13.45 + 2.45*10

f(10) = 37.95 million metric tones aquaculture in the whole world

China was responsible for 70.2% of world aquaculture thus China was responsible for 70% of 37.95 million metric tones aquaculture

(70.2/100)37.95 = 26.6409 million metric tones aquaculture

in the year of 2001 China was responsible for 26.6409 million metric tones aquaculture.