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Answers
Step-by-step explanation:
1)let no or article = x
real profit=(x-5)2-5(900/x)
given profit = 80
therefore(x-5)2-5(900/x)= 80
2x-10-4500/x= 80
2x^2 -10x- 4500=80x
x^2 -5x-22503=40X
x^2-45x- 2250=0
x^2-75x+30x-2250=0
(x-75)(x+30)=0
therefore, number of articles=75
2)Let the present age of the man and his son be'm' years and's' years respectively.
Two years ago,
Man's age = (m-2)
Son's age = (s-2)
(m-2)=3(5-2)
m-2=352 - 125 + 12
m=35-125 + 14
Three years later,
Man's age = (m+3)
Son's age = (+3) m+3=4(s +3)
m-4s =9
Equation
4s +9=35 - 12s + 14
3s^2- 16s +5=0
35 - 15s -5+5=0
3s(s-5)-1(s-5 )=0
(3s-1)(s-5)=0
S=5,
s= Not possible!
..s =5 years
m= 29
Present age of man =29years
Present age of son = 5 years
3)refer attachment
your answer is in the attachment
HOPE IT HELPS YOU
