Question 190313
Let the current ages be "x" and "y"  (x for father, y for son)
Given
{{{(x-10) = 7(y-10)}}}
{{{x-10 = 7y - 70}}}
{{{x - 7y = -60}}}

and
{{{2(x+2) = 5(y+2)}}}
{{{2x + 4 = 5y + 10}}}
{{{2x - 5y = 6}}}

*[invoke solving_linear_system_by_substitution 1, -7, -60, 2, -5, 6]