Question

pls answer me pls guys​

Answer 1

Answer:

7. Hari and Harry's ages are 20 and 28 respectively.

8. 13/21

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Step-by-step explanation:

7.

Hari's present age = n

Harry's present age = m

n:m = n/m = 5a/7a

(we can multiply both by any unknown number without changing its value. )

n + 4 = (5a+4)

m + 4 = (7a + 4)

(5a+4)/(7a+4) = 3/4

(3/4 is the ratio of their ages AFTER 4 yrs)

$\frac{5a + 4}{7a + 4} = \frac{3}{4} \\4(5a+4) = 3(7a+4)\\20a + 16 = 21a + 12\\20a - 21a = 12 - 16\\-a = -4\\a = 4\\5a = 20\\7a = 28$

hence, the ages of Hari and Harry are 20 and 28 respectively

8.

numerator = a

denominator = a+8

new numerator = a+17

new denominator = (a+8)-1 = a+7

new rational number = 3/2

hence,

$\frac{a+17}{a+7} = \frac{3}{2} \\2(a+17) = 3(a+7)\\2a + 34 = 3a + 21\\2a-3a = 21-34\\-a = -13\\a = 13$

numerator = a = 13

denominator = a+8 = 13+8 = 21

original rational number = 13/21