18$-8$book=20pencils that were 10$.
and Brian had 80 cards work: 80÷2= 40+10 new cards=50 cards
( 2a + 3 ) - ( 4a - 8 ) = 7
2a + 3 - 4a + 8 = 7
-2a + 11 = 7
-2a = -4
a = -4 / -2
a = 2
Simple, finding markdown, use these two formulas.
Markdown=Original-New
and
Percent Markdown= Markdown Amount/Original*100
So,
Markdown=612-450
M=162
Markdown%= 162/612*100
M%=0.2647*100
M%=26.5 (rounded)
Thus, there was a 26.5% decrease.
Assignment: 
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Answer: 
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Explanation: 
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[ Step One ] Multiply

[ Step Two ] Rewrite Equation

[ Step Three ] Multiply

[ Step Four ] Simplify

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Answer:x=-4 and x=4
Step-by-step explanation:
Took the assignment on edg 2020