Vivian combined different amounts of white paint, blue paint, and green paint to make 145 milliliters (ml) of paint of a new shade. The amount of white paint was x ml. The amount of blue paint was 10 ml less than twice the amount of white paint, and the amount of green paint was half the amount of blue paint. This is represented in the equation below.
x + (2x – 10) + 1/2 (2x – 10) = 145
What was the difference in the amounts of white paint and blue paint Vivian combined?

30 ml

35 ml

40 ml

45 ml

Question

Vivian combined different amounts of white paint, blue paint, and green paint to make 145 milliliters (ml) of paint of a new shade. The amount of white paint was x ml. The amount of blue paint was 10 ml less than twice the amount of white paint, and the amount of green paint was half the amount of blue paint. This is represented in the equation below. 
x + (2x – 10) + 1/2  (2x – 10) = 145
What was the difference in the amounts of white paint and blue paint Vivian combined?

 30 ml

 35 ml

 40 ml

 45 ml

anonymous · Answer

" x " - amount of white paint
"2x-10" - amount of green paint
"1/2 ( 2x -10)" - amount of blue paint

anonymous · Answer

difference means subtracting one from the other

jim_thompson5910 · Answer

x + (2x – 10) + 1/2 (2x – 10) = 145

x + (2x – 10) + 1/2 (2x) – 1/2(10) = 145

x + 2x – 10 + x – 5 = 145

4x – 15 = 145

I'll let you finish solving for x

anonymous · Answer

@jim_thompson5910 is solving for x really necessary?

jim_thompson5910 · Answer

yes, you need to know how much white paint there is

anonymous · Answer

if blue paint is 
x-5

and white paint is x

then the difference would be ...

jim_thompson5910 · Answer

btw, it says "The amount of blue paint was 10 ml less than twice the amount of white paint", so 

amount of blue paint:  2x - 10

jim_thompson5910 · Answer

you mixed up blue and green

anonymous · Answer

ah i see
crap

jim_thompson5910 · Answer

no biggie, you just got a free color out of it: yellow

anonymous · Answer

@jim_thompson5910 I did something wrong i got 15 :/

anonymous · Answer

wait no its 40 right?@jim_thompson5910

jim_thompson5910 · Answer

4x – 15 = 145

4x = 145+15

4x = 160

x = 160/4

x = 40

so you have 40 mL of white paint

amount of blue paint: 2x - 10

amount of blue paint: 2*40 - 10

amount of blue paint: 60 - 10

amount of blue paint: 50

-------------------------

Difference:  (amount of blue) - (amount of white)

Difference:  (50) - (40)

Difference:  10

hmm but 10 isn't an answer choice

jim_thompson5910 · Answer

oops typo lol one sec

jim_thompson5910 · Answer

amount of blue paint: 2x - 10 

amount of blue paint: 2*40 - 10 

amount of blue paint: 80 - 10 

amount of blue paint: 70

---------------------------------

Difference: (amount of blue) - (amount of white) 

Difference: (70) - (40) 

Difference: 30

jim_thompson5910 · Answer

there, fixed

anonymous · Answer

oh okay i get it thank you (: