Write an inequality and solve.

On the last three chemistry exams a student scored
81, 85, and 91. What score must the student earn on
the next exam to have an average above 85?

Step-by-step explanation:

Let x be the next exam's score.

We have 81 + 85 + 91 + x > 4(85).

=> 257 + x > 340

=> x > 83

Therefore the student must score above 83.

over the argument its not good to fight.

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