A man is four times as old as his son. Five years ago, the man was seven times as old as the son. a) How old are they now
b) How old were they five years ago

this is the answer b

Step-by-step explanation:

Let the present ages of Father and son be 4x and x (Given in the question). 5 years ago means (-5 from the present age).

F/S=4x/x [Equation 1]

Given 5 years ago the age of Father and son was 7y : y .

This implies,

(F-5)/(S-5) =7y/y [equation 2]

Sub 1 in 2,

(4x-5x)/(x-5)=7y/y (y gets cancelled)

4x-5=7x-35

35–5=7x-4x

30=3x

X=10

Present age F and son are 40 and 10.

Please delete didn't mean to answer

Step-by-step explanation:

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation: