Math-how this was solved? i need clear answers plz (5-5)?

Question

A certain preparation consists of liquids x, y, and z in the proportion 5:2:1. How many gallons of the preparation can be made from a stock of materials consisting of 25 gallons of x, 20 gallons of y, and 8 gallons of z?

A.25
B.40
C.80
D.53
E.50

answer: B

Answer 1

You have to find which element is the limiting element. It's X, BTW.

Assume it's Z
so 8 g of Z means 16 g of Y and 40 g of X, so it can't be Z...Not enough of X
Assume it's Y
so 20 g of Y means 10 g of Z and 50 g of X, so it can't be Y...Not enough of Z nor X
So it has to be X
so 25 g of X means 10 g of Y and 5 g of Z
25 + 10 + 5 = 40

Answer 2

My calculations give a figure of 23. Divide the 25 by 5 = 5, 20 Div by 2 = 10 and 8 div by 1 = 8 Add together gives 23 gallons

Answer 3

for every 5 gallons of X you need 2 of Y and one of Z, with the supply you listed we can use all 25 gallons of X, to find out how much Y we need take the amount of X we are using divide by the propotion amount of X and multiply by the propotion amount of Y. In this case we have 25/5 * 2 =10 Gallons of Y, repeat that step to find we will be using 5 gallons of Z
25 Gal of X + 10 Gal of Y + 5 Gal of Z makes 40 gallons of solution