## Elementary Geometry for College Students (5th Edition)

$x=7$
$m\angle 1+m\angle 2=90^{\circ}$ because two acute angles of a right triangle are complementary putting given values $7x+4+5x+2= 90^{\circ}$ $12x+6=90^{\circ}$ $12x=90-6$ $12x=84$ $12x=84\div12$ $x=7$