If AD = 6, DC = 14, and BE = 4.75, calculate EC. Image not set to scale.

Step-by-step explanation:

The triangles are congruent, we can use ratios to solve.

AD/DC = BE/EC

Let the length of EC be x.

6/14 = 4.75/x

Solve for x.

Cross multiply.

6 × x = 14 × 4.75

6x = 66.5

Divide both sides by 6.

(6x)/6 = (66.5)/6

x = 11.083333...

Greetings from Brasil...

Here we can use similarities of triangles

AC/DC = BC/EC

20/14 = (4.75 + X)/X

X ≅ 11.1

see attachment

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50