Can u just post the whole question or elaborate further
Answer:
2
Step-by-step explanation:
Plug 4 in for d and 3 in for c
5d-2/3c
5(4)-2/3(3)
Multiply in the numerator and the denominator
20-2/9
Subtract in the numerator
18/9
2
Hope this helps! :)
Answer: 10
<u>Step-by-step explanation:</u>
varies directly means: 
Step 1: solve for k ⇒ 
Step 2: plug in the given value and k to solve for the missing value: 
42(5) = 21(x)

2(5) = x
10 = x