Question 1184987
{{{7200=a+b}}}
{{{0.06a+0.12b=546}}

solve for one of the accounts (a) or (b) then substitute that into the other equation
{{{7200=a+b}}}
{{{7200-a=b}}}
{{{0.06a+0.12b=546}}}
{{{0.06a+0.12(7200-a)=546}}} multiply in
{{{0.06a+864-0.12a=546}}} add the variables
{{{-0.06a+864=546}}} subtract 864
{{{-0.06a=-318}}} divide by -0.06
{{{highlight(a=5300)}}} take this and put in first equation
{{{7200=a+b}}}
{{{7200=5300+b}}}subtract 5300
{{{highlight(1900=b)}}}