Question 121718
{{{g}}} = girl's age now
{{{f}}} = father's age now
{{{f = 4g}}}
{{{g + 7 = (1/2)*(f - 12)}}}
{{{g + 7 = (1/2)*(4g - 12)}}}
{{{g + 7 = 2g - 6}}}
{{{g = 13}}} answer
{{{f = 4g}}}
{{{f = 52}}} answer
check:
{{{g + 7 = (1/2)*(f - 12)}}}
{{{13 + 7 = (1/2)*(52 - 12)}}}
{{{20 = 20}}}
OK