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TalkativeMercury6660

Express the average of three sister in term A of the first born in years, if the second was born 5years after the first and the third was born 5 after the second.

FerUpsilon5520

The average age of the three sisters

F being the age of the first born;

S being the age of the seconde born and S = F + 5;

T being the age of the third born and T = S + 5 = F + 10;

The average age of the three sisters = (F + S + T)/3

And you can express the average age of the three sisters in term of the first born by substitution.

PoissonKappa3551

Hello TalkativeMercury6660,

Thank you for asking us to help you!

This is what we know :

First born = a

Second born = a-5

Third born = a-5-5

Now, to calculate the average, you need to find the sum of the age of the three siblings and divide them by 3.

I hope my explanation helped you, good luck :)

Laura Cristina