I Actually spent a hour trying to write an answer as it also challenged me, then i saw how simple it is i wish i could take back my time
Anyways, to find out the amout a medium smoothie cost we need to find the equation for it. With the given information we can find out that the cost of 4 medium smoothies is the same as 2 jumbos and one smoothie.So first lets find out the cost of 2 smoothies, 4.95 * 2 = 9.9.Now lets plot them into an equation.
4x+0.15=9.9+x
Simplyfy the equation by removing the x from the right side
4x-x=3x x-x=0
so now our new equation is
3x+0.15=9.9
Next lets remove the 0.15
0.15-0.15 = 0 9.9-0.15=9.75
so our new equation is now
3x=9.75
Then, we simplify the x by dividing the amount of x's it has
3x/3=x 9.75/3=3.25
So, after doing all that math, we found out that x=3.25
So each smoothie costs $3.25
so, the equation would be 4x+0.15=9.9+x
We can test it out by plotting in the situation
(3.25*4)+0.15=13.15 9.9+3.25=13.15
Don't forget to add the extra amount.
I am so glad i was able to find this out, and hope this helps you, as i had trouble with it myself, and thats coming from someone who's taking honors!