The sum of Sally's age plus Thomas's age is 12. The difference of Sally's age and Thomas's age is 3. Writeand solve a system f equations to find their ages. Interpret the solution.

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Let

Sally's age = s

Tomas's age = t

The sum of sally's age plus twice tomas's age is 12

s+2t=12 ... (1)

The difference of sally's age and tomas' is 3.

s-t=3

s=3+t ... (2)

Put the value of s from (2) to (1)

s+2t=12 ... (1)

3+t+2t=12

3t=12-3

3t=9

t=9/3

t=3

Put the value of t in (2)

s=3+t

s=3+3

s=6

Sally's age = s = 6

Tomas's age = t = 3