Q. Xin is the oldest of four siblings whose ages are consecutive integers. If the sum of their ages is 78, find Xin's age.Answer:
Denote Xin's age: Let's denote Xin's age as X. Since the siblings have consecutive ages, the other three siblings' ages would be X−1, X−2, and X−3. We are given that the sum of their ages is 78. The equation representing the sum of their ages is: X+(X−1)+(X−2)+(X−3)=78
Simplify and solve: Now, let's simplify and solve the equation:4X−6=78Add 6 to both sides to isolate the term with X:4X=78+64X=84
Divide and calculate: Next, we divide both sides by 4 to solve for X:X=484X=21
Final result: Xin's age, being the oldest, is the value of X we just calculated, which is 21 years old.
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