Identify the variable(s), set up your equation(s), and solve. Richard has an elder sister who is twice his age and a younger sis
ter who is two years younger than him. If the product of his sisters' ages is 70, how old is Richard?
1 answer:
Answer:
7 years
Step-by-step explanation:
Given that:
Let Richard's age = x
Elder sister's age = 2x
Youngwr sister's age = x - 2
Product of sisters ages = 70
2x * (x - 2) = 70
2x² - 4x = 70
2x² - 4x - 70 = 0
x² - 2x - 35 = 0
x² - 7x + 5x - 35 = 0
x(x - 7) +5(x - 7) = 0
(x - 7) or (x + 5) = 0
x = 7 or x = - 5
X can't be negative
Hence, x = 7
Richard is 7 years
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