Use a calculator called symbolab.com
Answer:
18. Commutative property of addition
19. Distributive property
20. Associative property of addition
Step-by-step explanation:
There are 12 wheels on 4 tricycles.
The answer should be y=-1/7x
Out of 960 calculators, 8 were found be to defective
Probability:

0.00833...
As a Percent:
0.00833....× 100
0.833%
To the nearest tenth of percentage:
0.833% ≈ 0.8%