if the lengths of triangle RST are r, s and t, where r=2, s=4, and t is an integer, what is one possible value of r+t/s?

The sum of any two sides of a triangle has to be greater than the third side

so 2+4 >t
t< 2+4
t < 6

and
2+t > 4

t > 2
since t in an integer, the only possible values of t
are 3,4, or 5
so one value of r+t/s = 2 + 4/4 = 3
unless you mean (r+t)/s
then it would be (2+4)4 = 3/2