Answers

  • Brainly User
2016-02-04T20:31:27+08:00
Present ages:
Tina: x
Robert: 4x

In 10 years:
Tina: x + 10
Robert: 4x + 10

Equation:
   
    4x + 10 = 2(x + 10)
    4x + 10 = 2x + 20
    4x - 2x =20 - 10
    2x = 10
    2x/2 = 10/2
    x = 5

Substitute 5 for x.
Present Ages:
Tina: x = 5 years old
Robert: 4(5) = 20 years old

ANSWER:  Robert is 20 years old now.

Check:
Ages in 10 years:
    Tina: 5 + 10 = 15 years old
    Robert: 20 + 10 = 30 years old

In 10 years, Robert's age is twice as Tina:
30 = 2(15)
30 = 30

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