by MARIA
(SALT LAKE CITY, UT)
Alvin's age is three times Elga's age. The sum of their ages is " 40 ". What is Elga's age?
Let x be Alvin's age
Let y be Elga's age
x + y = 40
x = 3y
Replace x = 3y into x + y = 40
We get 3y + y = 40
4y = 40
4y/4 = 40 / 4
y = 10
So Elga is 10 years old
Alvin's age is x = 3y = 3 times 10 = 30
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