Al gebra word problem

Question

Mary is 4 years older than John. Mr Smith is 5 times as old as John. If John is xyears old, how old is (a) Mary (b) Mr Smith? If the sum of the three ages is 60years, find how old John is.

 

Answer 1

Variables:

M = Mary's age

J = John's age (x)

S = Smith's age

 

Given:

M = J+4 = x+4 

S = 5J   =5x 

J = x      

M+S+J = 60

 

Find:

(a) M

(b) S

(c) J

 

First, find x:

   M    + S   + J = 60   substitute the first three givens into the fourth 

(x+4) + 5x + x = 60    combine like terms

7x + 4 = 60       subtract 4 from both sides

7x = 56     divide both sides by 7

x= 8

 

Now you can find everyone's age:

(a) M = x+4 = 8+4 = 12   Mary is twelve years old.
(b) S = 5x = 5(8) = 40          Mr. Smith is twenty years old.
(c) J = x = 8                         John is twelve years old.

 

 

 

 

Check : 12 + 40 + 8 = 60