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marys sister is 7 years older than mary. their combined ages add up to 35. how old is mary? solve the problem by writing and solving the equation.

Respuesta :

Mcawesom
let Mary be X years old
let Mary's sister be Y years old
Mary's sister is 7 years older than Mary
Y= 7 + X
their combined ages add up to 35
Y + X = 35
7 +X + X = 35
7 + 2X =35
2X = 35 - 7
2X = 28
X = 14
Y = 7 +X
Y = 7 + 14 = 21
Mary is 14 while Mary's sister is 21
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