a group of 11 students bought either chocolate chip cookies for forty cents each or brownies for fifty cents. The total amount they spend was five dollars and ten cents.How many chocolate chip cookies and brownies did they buy?

Let c be the number of chocolate chip cookies, and b be the number of brownies.

b + c = 11

0.4 * c + 0.5 *b = 5.10

Use algebra to solve for b and c

To solve this problem, we can use a system of equations. Let's use the variables "c" to represent the number of chocolate chip cookies and "b" to represent the number of brownies.

From the given information, we know:
1. The number of chocolate chip cookies and brownies adds up to 11: c + b = 11
2. The total cost of the cookies and brownies is $5.10: 0.40c + 0.50b = 5.10

Now we can solve this system of equations. Here's one way to do it:

Step 1: Solve the first equation for one variable in terms of the other.
c = 11 - b

Step 2: Substitute this expression for "c" into the second equation:
0.40(11 - b) + 0.50b = 5.10

Step 3: Distribute:
4.40 - 0.40b + 0.50b = 5.10

Step 4: Combine like terms:
0.10b = 0.70

Step 5: Solve for "b":
b = 0.70 / 0.10
b = 7

Step 6: Substitute the value of "b" back into the first equation to solve for "c":
c + 7 = 11
c = 11 - 7
c = 4

Therefore, they bought 4 chocolate chip cookies and 7 brownies.