They should have asked Laverne and Shirley. All the sides of an equilateral triangle are the same.
Call Squiggy's sides x and Lenny's sides x+10. The perimeter of S's triangle is 3x and the perimeter of L's triangle is 3(x+10) = 3x + 30.
The sum of the perimeters is 3x + 3x +30 = 186 (solve for x)
6x = 156 and x = 26.
S's triangle has sides of 26 for a perimeter of 78. L's triangle has sides of x+10 = 36 and a perimeter of 108.