I'm pretty sure the answer is 12.
Lowest common denominator for 3,4,6 is 12
5/6 = 10/12
1/4 = 3/12
2/3 = 8/12
a)
10/12 + 3/12 = 13/12 = 1 1/12
So you need to use first and second cables
b)
3/12 + 8/12 = 11/12
To reach 1 yard Carl need 1/12 yard cable
25 + 100i is correct because -5 squared is 25 and the the square root of -100 is 100i or 10i in its simplest form.
IN A triangle, sum of all angles = 180 degrees
2x + 3 + 4x+2 + 2x -1 = 180
8x +4 = 180
8x = 176
x = 176 /8 = 22 degrees
the angles are A = 2(22)+3 = 44+3 = 47 DEGREES
B = 4(22)+2 = 88 + 2 = 90 DEGREES
C = 2(22) -1 44-1 = 43 DEGREES