Answer: 37
Step-by-step explanation: The definition of a rhombus states that all 4 sides are equal so if you find the length of JK it will be the same as KL. To find it you have to set x+30 equal to 4x+9. Sp your equation should be 4x+9=x+30. if you subtract 9 from both sides and subtract x from both sides you get 21=3x. Then you divide both sides by 3 and get x=7. Substitute x=7 into one of the sides (chose x+30) and you have 3+30=JK so 33. And JK=KL so KL = 37