Question

Lady is twice as old as mary. Five years ago lady was 3 times as old as mary. How old is each girl now

Answer 1

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

Answer 2

Lady is 20 and Mary is 10

Explanation:

Let l = lady's age

Let m = mary's age

l = 2m

l-5 = 3(m-5) I need to subtract 5 from both Lady and Mary's ages to show 5 years ago

l - 5 = 3m - 15 Substitutes 2m for l

2m - 5 = 3m - 15 Subtract 2m from both sides

-5 = m - 15 Add 15 to both sides

10 = m

Mary is 10.

l = 2m Substitute 10 for m

l = 2(10)

Lady is 20.

Helping in the name of Jesus.