can someone please help me with this ?? im really confused but i need to pass this test!

In the circle above, the measure of angle DHG can be represented by 7x - 7, and the measure of arc DG can be represented by 9x + 21. The measure of arc DG is ___ degrees.

can someone please help me with this im really confused but i need to pass this test In the circle above the measure of angle DHG can be represented by 7x 7 and class=