Question 1143571: Lester is older than John by 7 years. 15 years back John's age was 3/4 of Lester's age. Find their present ages. Found 3 solutions by mathmadeeasy, MathTherapy, ikleyn:Answer by mathmadeeasy(2) (Show Source):
You can put this solution on YOUR website! Let L = Lester's present age
J = John's present age
Given:
1. Lester is older than John by 7 years: L = J + 7
2. 15 years back John's age was 3/4 of Lester's (present) age: J - 15 = 3/4 L
Solution:
I. L = J + 7
J - 15 = 3/4L
L = J + 7
J = 3/4L + 15
II. L = 3/4L + 15 + 7
L = 3/4L + 22
L - 3/4L = 22
4/4L - 3/4L = 22
1/4L = 22
4*(1/4)L = 22*4
L = 88
Testing the given:
1. L = J + 7
88 = J + 7
88 - 7 = J
J = 81
2. J - 15 = 3/4L
81 - 15 = 3/4(88)
66 = 66
Fifteen years back, John's age (was 66) was 3/4 off Lester's (present) age of 88.
Answer:
Lester's present age is 88 while John's present age is 81.
You can put this solution on YOUR website! Lester is older than John by 7 years. 15 years back John's age was 3/4 of Lester's age. Find their present ages.
It's more likely that this should've read: ".........15 years back John's age was 3/4 of Lester's age," then/at that time!
Having said that, that person's answers are INCORRECT.
Correct answers:
Let L be the Lester's age; then the John's age is L-7 years.
15 years back John's age was ((L-7)-15) = L-21; Lester's age was L-15 years.
The condition says
L - 22 = .
Solve this equation step by step. Start multiplying both sides by 4.
4L - 88 = 3*(L-15)
4L - 88 = 3L - 45
4l - 3L = 88 - 45
L = 43.
ANSWER. Lester is 43 years old; John is 43 - 7 = 36 years old.
CHECK. 43 - 15 = 28; 36 - 15 = 21; 21 = . ! Correct !
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