The interior angle measures of a pentagon form an arithmetic progression. The difference between the largest and smallest angle measures is 68 degrees. Find the measure of the smallest angle, in degrees.

Sum of interior angles of pentagon = 540

angle 1 to angle 5 is four common differences and = 68 68/4 = d = 17

a + a + d + a + 2d + a + 3d + a + 4d = 540

5a + 10d = 540 but d = 17

5a + 10(17) = 540

a = 74^{o}