Answer:
The letter "x" is often used in algebra to mean a value that is not yet known.
Step-by-step explanation:
x = 24
∠ 13 and ∠ 14 are adjacent angles on a straight line and sum to 180° , then
4x + 11 + 3x + 1 = 180 , that is
7x + 12 = 180 ( subtract 12 from both sides )
7x = 168 ( divide both sides by 7 )
