Answer:
The lemonade costs 1.4.
Step-by-step explanation:
This question is solved using a system of equations.
I am going to say that:
x is the cost of a cookie.
y is the cost of a lemonade.
Total cost for cookie and lemonade is 1.80.
This means that [tex]x + y = 1.8[/tex].
As we want y, we have that [tex]x = 1.8 - y[/tex]
Lemonade costs 1.00 more than the cookie?
This means that:
[tex]y = x + 1[/tex]
So
[tex]y = 1.8 - y + 1[/tex]
[tex]2y = 2.8[/tex]
[tex]y = \frac{2.8}{2}[/tex]
[tex]y = 1.4[/tex]
The lemonade costs 1.4.