Find the measure of angle

in the figure below. Enter only the number.

The image has three lines that intersect at point G. The line A B passes through points A, G and B. Line C E passes through points C, G, and E. Line D F passes through points D, G, and F and is perpendicular to line C E at point G. The angle A G C is labeled 51 degrees.

The solution is

The measure of angle EGF is 90 degrees.