-3z + 7 = -7 - 10z
Add 10z to both sides
7z + 7 = -7
Subtract 7 from both sides
7z = -14
Divide by 7
Z = -2
Answer:
cups of pineapple juice .
Step-by-step explanation:
Equation of direct proportion between x and y:

As per given,
Let x = quantity of pineapple juice and y = quantity of orange juice.
,
, 
Put these values in an equation we get

Hence, he needs
cups of pineapple juice .
The median is the moddle number of a data set. If the number of numbers is even add the 2 middle numbers and divide by 2.
Median = (7+7)÷2 = 7
The mean is the averagw value in a data set. You find it be adding all the numbers and then divide the answer by the number of numbers.
Mean: (6+6+6+7+7+7+8+8+8+9) ÷ 10
= 72 ÷ 10 = 7.2
Happy to help! Marking my answer as the Brainliest would really be aprreciated.