Answer:
$3
Step-by-step explanation:
Let c represent the cost of a box of cereal and let m represent the cost of a jug of milk.
Create a system of equations:
2c + m = 8.5
3c + 2m = 14
Solve by elimination by multiplying the top equation by -2:
-4c - 2m = -17
3c + 2m = 14
Add them together and solve for c:
-c = -3
c = 3
So, a box of cereal costs $3
Swapping rows alters the sign of the determinant:

Multiplying a single row by a scalar scales the determinant by the same amount:

Then

Answer:
6 weeks
Step-by-step explanation:
Total savings= $325
For every week, his total savings decrease by $28.
Let's form an expression for the amount of money left in his account after w weeks.
325 -28w= 157
28w= 325 -157
28w= 168
<em>Divide by 28 on both sides:</em>
w= 168 ÷28
w= 6
Thus, there are 6 weeks until he has $157.