The length of the segment RT is the sum of the lengths of RS and ST:
RT = RS + ST
We have:
RT = 56
RS = 2x + 18
ST = 24
So, using those expressions, we find:
RT = RS + ST
56 = 2x + 18 + 24
56 = 2x + 42
Now, to solve this equation, we can apply a sequence of the same operations on both sides of the equation, until we isolate the variable x and find its value:
56 = 2x + 42
56 - 42 = 2x + 42 - 42
14 = 2x
14/2 = 2x/2
7 = x
x = 7
Therefore, x = 7.