Solve for x.

For the one on the right you should use similar triangles.

Assuming that RST  is similar to MLK

Note that

RS / ST   =  ML / LK     ....so we have that...

[4x + 8 ] / 52  = 55 / 65

[4x + 8 ] / 52  =  11/13     cross-multiply

13 [ 4x + 8 ]  = 52 * 11     simplify

52x + 104  =  572     subtract  104  from both sides

52x  =  468      divide both sides by 52

x  = 9

Second one..if DC is parallel to SR....then triangle CDE  is similar to triangle SRE

So

CE / DE  = SE / RE

65 / 70  =  [9x + 3 ] /42

13/14  = [ 9x + 3] / 42     cross-multiply

42 * 13  = 14(9x + 3 ]  simplify

546  = 126x + 42   subtract 42 from both sides

504  = 126x     divide both sides by 126

4  = x