we know that
The sum of the internal angles of the triangle is equal to [tex]180[/tex] degrees
in this problem we have
m∠2=[tex]2x\°[/tex]
m∠3=[tex]5x\°[/tex]
m∠1+m∠2+m∠3=[tex]180\°[/tex]
Substitute the values and solve for m∠1
m∠1=[tex]180\°-(2x+5x)\°[/tex]
m∠1=[tex]180\°-7x\°[/tex]
Remember that
m∠1+m∠4=[tex]180\°[/tex] -------> by supplementary angles
Substitute the value of m∠1 and find m∠4
m∠4=[tex]180\°-(180\°-7x\°)[/tex]
m∠4=[tex]7x\°[/tex]
therefore
the answer is
a) the measure of m∠1=[tex]180\°-7x\°[/tex]
b) the measure of m∠4=[tex]7x\°[/tex]
