Question 160978
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{{{A+B=90}}} ----> EQN 1
But, {{{A=4B}}} ---> EQN 2: 4 times the measure of its complement
Susbt. EQN 2 in EQN 1:
{{{4B+B=90}}}
{{{5B=90}}} -----> {{{cross(5)B/cross(5)=cross(90)18/cross(5)}}}
{{{B=18deg}}}
Go back EQN 2:
{{{A=4*18=72deg}}}
Check via EQN 1:
{{{72+18=90}}}
{{{90=90}}}
Thank you,
Jojo</pre>