Question 152350
We know complement angles form {{{90 degrees}}}
Let's make 2 angles as {{{angleA}}} & it's complement as  {{{angleB}}}
So, {{{(angleA)+(angleB)=90}}} -----------> working eqn
but, {{{angleA=4*angleB}}},= {{{A=4B}}}, then
{{{4B+B=90}}} -----------> {{{cross(5)B/cross(5)=cross(90)18/cross(5)}}}
{{{B=18deg}}}
And, {{{A=4*18=72deg}}}
In doubt? go back working eqn,
{{{72+18=90}}}
{{{90=90}}}
Thank you,
Jojo