Answer:
2400 mm
Step-by-step explanation:
(80 x 60) - (60 x 40)
429
y=3+6×(n-1)
n=72
y=3+6×(72-1) = 429
Equilateral triangle means each angle equals 60 degrees.
60 = 7x - 3
63 = 7x
x = 9
