Question

If 7a + 3b : 4a + 9b = 9: 7 then the value ofa+b/ a is _______
(A) 53/60
(B) 73/70
(C) 73/60
(D) 53/70
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Answer 1

The value of (a+b)/a = 73/60  

Option (c) is correct.

Step-by-step explanation:

7a + 3b / 4a + 9b = 9/7

Now simply the equation

49a + 21b = 36a + 81b

49a -36a = 81b -21b

13a = 60b  

b/a = 13/60

a = 60      

Then (a + b)/a

Now put the value of a in above equation

(60+13)/60 = 73/60    

Thus the value of (a+b)/a = 73/60

Learn more about this question.

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Answer 2

Answer:

(C) 73/60

Step-by-step explanation:

Given,

7a + 3b : 4a + 9b = 9: 7

$\implies \frac{7a + 3b}{4a+9b}=\frac{9}{7}$

$49a + 21b = 36a + 81b$

$49a - 36a = 81b - 21b$

$13a = 60b$

$\frac{b}{a}=\frac{13}{60}$

Adding 1 on both sides,

$\frac{b}{a}+1 = \frac{13}{60}+1$

$\frac{a+b}{a}=\frac{13+60}{60}$

$\implies \frac{a+b}{a}=\frac{73}{60}$

Hence, OPTION C is correct.