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David is twice as old as Sara, and Jessica is three times as old as Sara. If their ages add up to 30, how old is David?

x = Sara's age
2x = David's age
3x = Jessica's age

Respuesta :

mysticaldogg
x + 2x + 3x = 30
combine like terms

6x = 30
divide both sides by 6 to isolate the variable

x = 5

Sara is 5
David is 10
Jessica is 15