23 Pennie’s is the answer I believe
Answer:
There are 23 dimes in the box
Step-by-step explanation:
Let nickels=n
Let dimes=(35-n)
Equation: 0.05n+0.10(35-n)=2.90
Multiply both sides by 100: 5n+10(35-n)=290
-5n+350=290
-5n=-60
n=12
35-12=23
Therefore, there are 23 dimes in the box
I would estimate it as (300 x 7) = 2100
Then I would subtract (11 x 7) + 77 from that to get the exact answer of 2023
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I didn't use a calculator or paper. The 'trick' is to notice that 289 = (300 - 11)
The answer is 15 cookies and 5 brownies
If you notice the picture below, the amount of fencing, or perimeter, that will be used will be 3w + 2l
now

solve for "w", to see what critical points you get, and then run a first-derivative test on them, for the minimum
notice the

so. you can pretty much skip that one, though is a valid critical point, the width can't clearly be 0
so.. check the critical points on the other