if 7a+3b : 4a+9b then value of a+b/a
Answers
Answer:If a:b=3:5 and b:c=7:8 then 2a:3b:7c is equal to?
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The important thing is to write two variables in terms of the last variable
As a:b =3:5,
a=3b/5 ...(1)
b:c=7:8
c=8b/7 ..(2)
2a:3b:7c
=(6b/5):3b:8b (from (1) and (2))
2a:3b:7c=6:15:40
Step-by-step explanation:
Step-by-step explanation:
Given,
7a + 3b : 4a + 9b = 9: 7
\implies \frac{7a + 3b}{4a+9b}=\frac{9}{7}⟹
4a+9b
7a+3b
=
7
9
49a + 21b = 36a + 81b49a+21b=36a+81b
49a - 36a = 81b - 21b49a−36a=81b−21b
13a = 60b13a=60b
\frac{b}{a}=\frac{13}{60}
a
b
=
60
13
Adding 1 on both sides,
\frac{b}{a}+1 = \frac{13}{60}+1
a
b
+1=
60
13
+1
\frac{a+b}{a}=\frac{13+60}{60}
a
a+b
=
60
13+60
\implies \frac{a+b}{a}=\frac{73}{60}⟹
a
a+b
=
60
73
Hence, OPTION C is correct.