Question 121698
Let {{{m}}} = Mother's age now
Let {{{d}}} = daughter's age now
{{{m = 4d}}}
Read the 2nd part as: When both Mother and Daughter are
20 years older, The mother will be twice as old
{{{m + 20 = 2(d + 20)}}}
Substitute 1st equation into 2nd
{{{4d + 20 = 2d + 40}}}
{{{2d = 20}}}
{{{d = 10}}} daughter's age now
{{{m = 4d}}}
{{{m = 40}}} mother's age now
check:
{{{m + 20 = 2(d + 20)}}}
{{{40 + 20 = 2(10 + 20)}}}
{{{60 = 2*30}}}
{{{60 = 60}}}
OK