A real world example of using two-variable linear regression would be to estimate the amount of code written by several programmers. 
Let’s assume that senior programmers on average write 60 lines of code per hour, and junior programmers on average write 30.
Then, we can model the amount of code written using linear regression as y = 60 * s + 30 * j + 0 * i, 
where y is the amount of lines of code written in an hour, s is the number of working senior programmers, j is the number of working junior programmers, and i is the y-intercept, which has coefficient 0 in this case because without programmers, no lines of code are being written.
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