Answer:
Mary (x) = 10 yr old and Lady (y) = 20 yr old
Explanation:
let the age of Mary and lady be x and y respectively.
according to the question,
y = 2x ---- eqⁿ(1)
y = 2x ---- eqⁿ(1){given: lady (y) is twice as old as Mary (2x)}
y - 5 = 3(x - 5)
y - 5 = 3x - 15
y - 3x = - 10 ---- eqⁿ(2)
y - 3x = - 10 ---- eqⁿ(2){given : 5 years ago (therefore we will subtract 5 from both the sides) y was thrice the age of x}
through substitution method
we will substitute the value of y and insert it in eqⁿ(2)
now,
y - 3x = -10
y = 2x
2x - 3x = -10
- x = - 10
x = 10
y = 2x
y = 2(10)
y = 20