The perimeter of a triangle is 199 inches. if one side of the triangle is six more than the shorter side, and the longer side is 19 more than the shorter side, find the lengths of the three sides?

Shortest side (a) = 58
middle side (b) = 64
longest side (c) = 77

the 3 sides a + b + c = 199
b = a + 6
c = a + 19

substitute your new values for b & c into your original formula, so:
a + (a+6) + (a+19) = 199
3a + 25 = 199
3a = 174
a = 58

then substitute 58 into your b & c formulas to figure out the rest
b = a + 6 = 58 + 6 = 64
c = a + 19 = 58 + 19 = 77