The perimeter is 24 inches squared
The answer is 36 because you have to multiply it and divide getting your the answer.
The mountain will be at 80mm long in 50 years because 50 times 1.6mm equals 80
That would be tan
(1-cos)(1+cos)=1-cos² which equals to sin²
√sin²/cos²= sin/cos which equals to tan
Xy-3x=40, x=5
x(y-3)=40
y-3=(40/x)
y=(40/x)+3
y=(40/5)+3
y=8+3
y=11