Answer:
x = 21
Step-by-step explanation:
Because GJ is a diameter, the angle K is a right angle (90 degrees).
Thus, 4x + 6 = 90, and 4x = 84. Thus, x = 21
let's say the bill without the tip is "x" amount, so that'd be the 100% of the bill, but we also know that 4.50 is the 18% of "x".
so if 4.50 is the 18% of "x", how much is "x"?

The constant term should be +6