Book Maths Puzzle Age Problem

A mother is 6 times older than her daughter is today, and in 20 years from today, the mother will be twice the child's age. What is the daughter's age today? And, what is the equation for solving this problem?

Read Solution (Total 1)

Let m nd d be the present ages of mother nd daughter respectively
m = 6*d

After 20 years
(m+20) = 2*(d+20)
m = 2d + 20

Equate "m"
6d = 2d + 20
4d = 20
d = 5
m = 30

Ans : 5 years
10 years agoHelpfull: Yes(4) No(0)

Book Other Question

Your teacher is giving you a test worth 100 points containing 40 questions. There are 2-point and 4-point questions on the test. How many of each type of question are on the test? I know this is not algebra but if you can answer that would be great.
Q. A uniform rod with a 3.0 m length and a mass of 14.0 kg is supported by a hinge at its left end and held in a horizontal position. A mass of 6.0 kg is attached to the rod 0.36 m from the hinge. A second mass of 7.5 kg is attached to the rod 2.80 m from the hinge.
(A) Find the moments of inertia for each of the three masses about an axis at the hinge.
(B) At the instant the right end of the rod is released, what is the net torque acting on this system?
(C) What is the angular acceleration of this system the instant it is released?