The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try! so im pretty sure its 20
Add 7 to both sides
3x + 12 = 7x
Subtract 3x
12 = 4x
Divide by 4
x = 3
Tan(60)=Opposite or L /20cm
*20. *20
Tan(60)*20=L
34.64101615=L
34.64 (to the nearest hundredth of a meter or cm)