What is the constant of proportionality of
1. y=2.0+ 0.5x

2.y=75x
3.y=55x

4.y=320-15x

5. y= 15/60 x+30

6.y=2.25
7.y=5x+3

8.y=3-0.6x
9.y=15+ 1/2x
10.y=65x

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please do at least 5 .-.