Question 825667: manu is 4 years older than his sister anu. if the sum of their ages is 20 years, find their ages.
Answer by homeworkhedgehog(9)   (Show Source):
You can put this solution on YOUR website! For this, you can create two equations and solve them using substitution or elimination.
"Manu is 4 years older than his sister Anu" translates to
M = 4 + A
"The sum of their ages is 20 years" translates to
M + A = 20
Since we know that M = 4 + A, we can substitute that into "M" in the other equation:
(4 + A) + A = 20
Now we combine our "like" terms (the parentheses are negligible):
4 + 2A = 20
And solve for "A" using algebra.
Subtract 4 from both sides:
2A = 16
Divide both sides by 2:
A = 8
Now we know how old Anu is. She is 8 years old. We use this to find Manu's age. "Manu is 4 years older than Anu" tells us that Manu is 12. This checks out when we add 8 and 12 to see if their combined age is really 20 like the problem says.
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