How do you know that the absolute value of -|-9| is equal to -9?

Ashopper bought a watermelon a pack of napkins and some paper plates in his state there was no tax on food the tax rate on non-food items is 5% the total for the three items he bought was 825 before tags and he paid $0.19 in taxes how much did the watermelon cost

Me! 50 points! why does when we come home, our door is unlocked and there is grease on the door knob, me solve this , and i don't know what category this goes under

Solve the equation: x - 9 = -6 + 5 a. 21 b. 7 c. 14 d. 2