Let the functions $f, F, g, G,$ and $H$ represent the number of tons of carbon emitted per year as a function of year corresponding to cement production, natural gas, coal, petroleum, and the total amount, respectively. Let $t$ represent the year, with $t=0$ corresponding to $1900 .$
(GRAPH CAN'T COPY)
Estimate (to the nearest thousand) the value of
a. $F(50)$
b. $g(50)$
c. $H(50)$