Linear model is y = mx + b
So in year 1994, or x = 0, there was 51.7 billion eggs produced. This means that the y intercept is 51.7 billion, or b = 51.7.
m is the slope of the line. You need to find out the difference of egg production for change of y (numerator) and x is always 1 year. I suspect that this is anticipating that you are using a calculator to find the line of best fit. If you find the average rate of change over time, your prediction will be the already provided answer in the table.
2000 - 1999 = 69.8 - 64.1 = 5.7
1999 - 1998 = 64.1 - 60.6 = 3.5
etc.
or 2000 - 1994 = 69.8 - 51.7 = 18.1 divided by 6 years = 3.017 per year
then y = 3.017x + 51.7
y = 69.8 billion eggs
In a calculator, enter the data into a table, but use years of 0, 1, 2, etc. Then CALC, then LinReg for Linear Regression. It will give you an equation in y = mx + b format.