A model shows the visualize of what you need to do in order to complete the problem your asked. It can also show important steps and make it easier for you to answer the question, like length×height×width.
You distribute -4 to each in the parentheses then you get -24 - 4b = 4 then you add 24 on both sides and get -4b = 28 then you divide each side by -4 and it equals -7
103.468
Since 4 rounds down:
103
Hope this helps!
450 g in 2:13
<u>Total proportion asked for </u>=2+13=15
<u>Now comparing g with ratio, or whatever </u>
450/15=30g 
Therefore 1 in ratio depicts of 30g
So final answer = 
More to know, daily bit of knowledge: The Binomial Theorem:
Answer is 4/7
You divide the length of C'D' over the length of CD
C'D'/CD = 8/14 = 4/7
The scale factor is smaller than 1, so C'D' is shorter than CD
