Question 895094
By definition,
{{{A+C=90}}}
In this case,
{{{A=4C-20}}}
Substitute,
{{{(4C-20)+C=90}}}
{{{5C=110}}}
{{{C=22}}}
Then,
{{{A=4(22)-20}}}
{{{A=88-20}}}
{{{A=68}}}