By writing an equation you can easily solve this:
18+ X + 4X - 1 = 42
•we need the answer to 4X-1
1. put the parts that include the X parameter in one side and the integer numbers in one side :
X + 4X = 25
5X= 25
X= 5
2. 4X-1 —> 4x5-1 = 19
Need to take 25 mg times 18% then times it by 4 then times it again by .01
We see that CF and DE are parallel to each other, which means that they had the same length with each other, so:
6n-1=5n+9
Subtract 5n for both side
6n-1-5n=5n+9-5n
n-1=9
Add 1 for both side
n-1+1=9+1
n=10
CF=
6n-1
=6(10)-1
=60-1
=59
DE=
5n+9
=5(10)+9
=50+9
=59
CD/FE:
4n+2
=4(10)+2
=42
True/False:
n=10 True
n=7 False
CF=59 True
FE=42 True
CD=30 False. As a result, n=10;CF=59; and FE=42 is your final answer. Hope it help!