What is the measure DC?

20 feet

Step-by-step explanation:

Since they are two right triangles, you can prove that triangle BAD is congruent with triangle CAD through HL (hypotenuse leg)

BA = AC and AD = DA (with the reflexive formula)

Since they both have right angles, HL would be what proves that the two small triangles are congruent

Since BD = 20 feet then DC should also equal 20 feet since they are congruent triangles

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

the answer is a

step-by-step explanation: