Question

20) The ratio of a brother's and sister's age was 11:5, seven years back After
eight years, this ratio will be 7:4. What will be the sum of their ages 10 years
from now?​

Answer 1

Answer:

Hope it helps you

Step-by-step explanation:

say now, brother is x, sister is y.

then, 7yrs ago, (x-7)/(y-7)= 11/5 => 5x-11y=-42…(i)

and, 8yrs after, (x+8)/(y+8)= 7/4 => 4x-7y= 24…(ii)

solving (i) and (ii), x= 62, y= 32.

hence, the sum of their ages 10 years from now will be 72+42= 114.

you could as well think of simpler algebra: viz: 7 yrs ago the ages were 11x, 5x. 8yrs after they will be 11x+15, 5x+15=> (11x+15)/(5x+15)=7/4=> x=5.

thus 10 yrs hence, sum will be (11x+17)+(5x+17)=114.

Answer 2

hope it helps....

please mark my answer as BRAINLIEST.