First equation:
-5x -10 >= 15
divide both sides by -5
x+2 <= -3
x <= -5
Second equation:
2x +8 < 10
2x < 2
x < 1
If you're asking which values of x meet both requirements ( x <= -5 and x < 1) then the answer is x <= 5.
Note: If x meets the first requirement ( x <= -5 ), then the second requirement ( x < 1 ) doesn't do anything because x is already always less than 1.