Question 1150954
Let j = Jacob's present age
let b = brother's  "     "
:
Write an equation for each statement
:
 five years ago Jacob was one sixth of the age of his brother.
j - 5 = {{{1/6}}}(b-5)
j = {{{1/6}}}(b-5) + 5
multiply by 6 to get rid of the fraction
6j = b - 5 + 30
6j = b + 25
or we could write
b = 6j - 25
 In three years time, his age doubled, will match his brother age.
b + 3 = 2(j+3)
b + 3 = 2j + 6
b = 2j + 6 - 3
b = 2j + 3
replace b with (6j-25)
6j - 25 = 2j + 3
6j - 2j = 3 + 25
4j = 28
j = 28/4
j = 7 yrs is Jacob's present age
:
:
Check this, find b
b = 2(7) + 3
b = 17
Check in the statement
" In three years time his age doubled will match his brother age.
2(7+3) = 17 + 3
2(10) = 20