Well since we can use a base of 1 we know that 1 - 45 is less than 4 but -1 + 45 is not, which follows the assumption that x>0, but now we need to know what x is less than to fit the inequality. If we use 5 as a trial we can see that 5 - 9 = -4 so 0<x<5 is your answer. Hope this helps I basically used trial and error. If you want to check try 3 or 4 for x and it will work but 6 will not.
