Answer:
n = 12 1/4
Step-by-step explanation:
do you need me to explain it too? I can! XD ^_^
12x + 24y < = 240
** because 2 hrs and 120 minutes = 240 minutes
2.74x7.5=20.55=20.550
That's all of your answers.
Step 1. Multiply first equation with -3 and the second one with 2. You'll get:

Step 2. Add both equations together. You'll get:

, which gives x = -2
Step 3. Replace x = -2 in the first equation and calculate y.

The solution is: x=-2, y=5
Let x be the amount of cocoa you use in the recipe.
then 4x is the amount of flour used, and 5x is the amount sugar used.
x+4x+5x= 550g
10x=550g
x=55g
So, you use 55g of cocoa, 220g of flour, and 275g of sugar.
hope this helps! :)