Question 205841
m = Mary's age; b = Bob's age
:
Mary's age and Bob's age are in the ration 3:2.
{{{m/b}}} = {{{3/2}}}
cross multiply
2m = 3b
m = {{{3/2}}}b
or
m = 1.5b
:
 Eight years later, the ratio of their ages will be 4:3.
{{{(m+8)/(b+8)}}} = {{{4/3}}}
Cross multiply
3(m+8) = 4(b+8)
3m + 24 = 4b + 32
3m = 4b + 32 - 24
3m = 4b + 8
:
 Find their present ages.
Replace m with 1.5b in the above equation
3(1.5b) = 4b + 8
4.5b = 4b + 8
4.5b - 4b = 8
.5b = 8
b = {{{8/.5}}}
b = 16 yr is Bob's present age
then
m = 1.5(16)
m = 24 yrs is Mary's present age
;
:
Check solution in the 8 yr equation
{{{32/24}}} = {{{4/3}}}