The doctor tells Marc that he needs to exercise enough to burn at least 200 calories each day. He prefers running or biking. While running he burns 15 calories per minute, and while biking he burns 10 calories per minute. Let x be the number of minutes he spends running and let y be the number of minutes he spends biking. Write an inequality that models this situation.

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you can first factor out the n to get n(1+5). we know that 1+5 is 6, so we just have 6n.

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional