Answer:
420
Step-by-step explanation:
volume = length x width x height
12 x 5 x 7 = 420
The sailboat would be fully depreciated when the 7th year comes when it was depreciated 15% every year. This is because when you try to multiply 15% by 7 it would give you 105%, it already exceeds the 100% value of the sailboat.
I believe your last coordinate would be (6,3)
move the 3 to the 7 side. it will become negative.
9x-5x=7-3
4x=4
x=1
