Question 875009
The key to the x values is "x is the number of years past 1990", therefore the two pairs of data points are (5, 48000) and (14, 58000).
The slope(m) is (58000 - 48000) / (14 - 5) = 10000 / 9
pick the point (5, 48000) and we solve the following for b (y intercept)
standard for for a line is y = mx + b
48000 = (10000/9)5 + b
multiply by 5
48000 = (50000/9) + b 
now multiply both sides of = by 9
432000 = 50000 + 9b
9b = 382000
b = 42444.4
the equation is y = (10000/9)x + 42444.4
now we test it with the second point
y = (10000/9)14 + 42444.4 = 57999.9 is approx 58000
the test checks out  :-)