A scholar observed that if the production of fertilizers in 1989 had been the same as that in 1988, then the total fertilizer production for all the given years would have been 450 million tonnes. Using this information, and knowing that the food production has been plotted on the same scale, one may say that the food production in 1983 was (approximately, in million tonnes) .

Let each unit in the scale be equal to X

So, fertilizer production in 1983 is 2.5X
So, fertilizer production in 1984 is 3.5X
So, fertilizer production in 1985 is 3.5X
So, fertilizer production in 1986 is 2X
So, fertilizer production in 1987 is 2X
So, fertilizer production in 1988 is 3.5X
Assuming fertilizer production in 1989 is same as that of 1988 it equals 3.5X
So, fertilizer production in 1990 is X
So, fertilizer production in 1991 is X
Hence, the total is 22.5X
But this equals 450 million tonnes. Hence, X = 20 million tonnes

Therefore, food production in 1983 = 6.5X equals 130 million tonnes