The percentage of women in the military

The percentage of women in the military who serve on active duty has been steadily increasing. The number of women N on the active duty force t years after 1971 is approximated by the formula: N = 12,197.8t + 44,000. How many women were in military in 1975 (t=4), 1978 (t=7), and 1991 (t=20)? For what years will the number of women be at least 400,000?

(Round all answers to nearest whole number.)
How many women were in the military in 1975 (t=4)?
the solution is N = 92791

How many women were in the military in 1978 (t=7)
N = 129385

How many women were in the military in 1991 (t=20)?
N = 287956

For what years will the number of women be at least 400,000?
The solution is {y l y > __}

Note the symbol > is with a line under it.