Question 257355
This is an RTD problem. We can create a table based on the given information
JET . . . . . . rate . . . . . . . . . .time . . . . . . . . . . . . . . . . distance
m->s . . . . R . . . . . . . . . . . .4000/R . . . . . . . . . . .. . . .. 4000
s->m . . . . R + 300 . . . . . . .4000/(R + 300) . . . . . . .. . .4000
totals . . . . . . . . . . . .. . . . . .. . .13
So, from the table, we get
{{{4000/R + 4000/(R+300) = 13}}}
multiply by common denominator to get
{{{4000(R + 300) + 4000R = 13(R)(R+300)}}}
simplifying, we get
{{{8000R + 1200000 = 13R^2 + 3900R}}}
setting = 0, we get
{{{13R^2 - 4100R - 1200000 = 0}}}
By quadratic, we get
R = 500