Question

2) Mr. Chavez bought 11 cookies. Chocolate cookies cost $3 and sugar

cookies cost $4. He spent a total of $35. How many of each type did
he buy?
Define Variables:
Write the system of equations:

Answer 1

3x+4y=35
x+y=11
x=choc cookies
y=sugar cookies
x+y=11 —> y=11-x
Substitute into other equation:
3x+4y=35
3x+4(11-x)=35
Solve for x
3x+44-4x=35
-x=-9
x=9
Then x+y=11
y=11-x=11-9=2
x=9, y=2
He bought 9 choc cookies and 2 sugar cookies.

Answer 2

Variables : C , S

Equations : C + S = 11

3C + 4S = 35

Explanation:

Chocolate cookies be = C

Sugar Cookies be = S

Total number of cookies : C + S = 11

Total Spent on the cookies : 3C + 4S = 35

`C + S = 11\\C = 11 - S\\3C + 4S = 35\\3(11 - S ) + 4S = 35\\33 -3S +4S = 35\\-3S + 4S = 35 - 33\\S = 2\\\\C + S = 11\\C + 2 = 11\\C = 9`