16. If (3a+6b)/(5a+12b) = 12/23 then (3a.a + 5b.b)/(a.b) = ?
a. 8.5
b. 9.5
c. 10.5
d. 11.5

• (3a+6b)/(5a+12b)=12/23
  after solving it
  69a-60a=144b-138b
  9a=6b
  a/b=2/3
  on the other side
  (3a^2+5b^2)/ab
  3a^2/ab+5b^2/ab
  3a/b+5b/a put the values, 9.5 ll be the r8 ans.
• 9 years agoHelpfull: Yes(8) No(1)
• ans- 3a+6b/5a+12b=12/23
  Cross multiply----then we get the value of a/b=2/3....hence a=2 and b=3....now put the valuem of a and b in que...we get the answer i.e 9.5
• 9 years agoHelpfull: Yes(1) No(0)
• 5a+12b=23----->eq 1
  3a+6b=12------>eq 2
  eq 1*3=15a+36b=69
  eq 2*5=15a+30b=60
  subtract two eqs we get b=3/2,a=1
  sub in (3a.a+5b.b)/(a.b) we get 17 ans
• 9 years agoHelpfull: Yes(0) No(3)
• 9.5 is the correct ans
• 9 years agoHelpfull: Yes(0) No(0)
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• 9 years agoHelpfull: Yes(0) No(0)