Dina is twice as old as Andrea. The sum of their age is 72. Find their present ages.

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Dina is twice as old as Andrea. The sum of their age is 72. Find their present ages.

Let d be Dina's age. Let a be Andrea's age. We're given:

1. d = 2a <-- Twice means multiply by 2
2. a + d = 72

Substitute equation (1) into equation (2):
a + 2a = 72

Type this equation into our search engine and we get:
a = 24

Substitute a = 24 into equation (1):
d = 2(24)
d = 48

So Andrea is 24 years old and Dina is 48 years old