Question 334747
{{{A+B=90}}}
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{{{A=4B}}}
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Substitute into the first equation and solve for B.
{{{4B+B=90}}}
{{{5B=90}}}
{{{B=18}}}
Then solve for A.
{{{A=4B=4(18)=72}}}
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A is 72 degrees, B is 18 degrees.