Hi Joaquin. My name is Ashley and I have broken down the problem below. Please let me know if you have any questions. The method here is to create equations, find the number of carbs in one glass of milk and 1 snack bar, and add them together at the end.
Step 1: Label your variables or your unknowns.
g- # of carbs in 1 glass of milk
b- # of carbs in 1 snack bar
Step 2: Create Equations. Since we have 2 variables, we need 2 equations. The equations are created based on the information the problem gave us
3 glasses + 4 bars = 86 carbs
3g+ 4b = 86
4 glasses + 3 bars = 82 carbs
4g+ 3b= 82
Step 3: Solve the Equations
Let's start with the elimination method and eliminate g.
3g+4b=86
4g+3b=82
We want to cancel g so we want to make sure that the number in front of g is equal with opposite signs.
-4(3g+4b=86)
3(4g+3b=82)
-12g-16b=-344
12g + 9b = 246
Add both equations. The g cancels out and you are left with b and the other side of the equation.
-12g - 16b = -344
12g + 9b = 246
Isolate b.
-7b = -98
-7b/(-7) = -98/(-7)
b = 14
Let's substitute b back into one of the original equations, so we can find g.
3g+4b=86
3g+4(14)=86
3g+56=86
3g= 86-56
3g=30
g=10
Step 4: Do a quick check by plugging both values into the original equation to make sure both sides are equal.
4g + 3b = 82
4(10) + 3(14)= 82
40+42 = 82
Step 5: Finally, remember that the problem wanted the number of carbs in one snack bar and one glass of milk. We have to add the values we found.
g + b = ?
10 + 14 = 24
There are 24 carbs in one glass of milk and one snack bar. I hope this helps.