RS and RT are both segments on the same line. Therefore their equation can be added together and set equal to the equation that is given representing the entire length of segment ST.:
4x+10+ -2x+24=4x+12
Now that you have created one larger equation to solve for x you can now go ahead and combine like terms, (all the x's with the x's and the regular numbers with the regular numbers)
2x+34=4x+12
Now you must move the variables and constants to the opposite sides of the equation. This is called isolating the variable:
2x= 22
Now you can solve for x by dividing by 2 and your answer is x = 11
Now that you have solved for the value of x you can take that value and plug it into the equation that is given for the length of segment RS.
-2X+24 NOW BECOMESSS......
-2(11)+24= -22+24= 2
The length of segment RS is 2
The length of segment RT is 54