Question

I need help with number 8,please.

Answer 1

Let x be equal to the number of drinks Yasmine consumed. 
Jose had 2 times that drink so his number of consumed drink would be represented by 2x.  
Sally had 3 fewer drink than Jose so her number of consumed drinks would be represented by 2x-3.
Altogether, the three of them consumed 72 drinks so your equation would be:
x+2x+(2x-3)=72
add like terms together:
5x-3=72
have the term with x be alone on one side of the equation, in this case by adding three to both sides:
5x=75
now divide both sides by five for the value of x and your answer is.....
x=15

Answer 2

Hi!

Okay, so let's break this down.

Jose drinks twice as many sodas as Yasmine. 
So we know, that..
2j = y

Sally drinks 3 fewer sodas than Jose.
j - 3 = s

The total number of sodas that they consumed is 72.
j + y + s = 72

Now let's try to put in some values. 

Since s = j - 3..
j + y + j - 3 = 72

Simplify..
2j + y - 3 = 72
2j + y = 75

Since y = 2j...
2j + 2j = 75

Simplify..
4j = 75
j = 18.75

Now check our solution. 
18.75 · 2 = s
37.5 = s

18.75 - 3 = y
15.75 = y

18.75 + 15.75 + 37.5 = 72
^the answer

Hope this helps! :)