4n-40=7(-2n+2)
4n-40=-14n+14
subtract -4n from both sides
-40 = -18n +14
subtract -14 from both sides
-54=-18n
divide both sides by -18
3 = n
15
63 x 5 = 315
315/20 = 15.75
hence, 15 $20 bills
Answer:
Step-by-step explanation:
You can split the coins into 3 groups, each of them has 3 coins. Weigh group 1 vs group 2, if one is lighter, that group has the fake coin. If both groups weigh the same, then group 3 has the fake coin.
Continue to split the group that has the fake coin into 3 groups, each group has 1 coin. Now apply the same procedure and we can identify the fake coin.
Total of scale usage is 2
b) if you have
coins then you can apply the same approach and find the fake coin with just n steps. By splitting up to 3 groups each step, after each step you should be able to narrow down your suspected coin by 3 times.
Step 1: you narrow down to group of
coins
Step 2: you narrow down to group of
coins
Step 3: you narrow down to group of
coins
...
Step n: Step 1: you narrow down to group of
coin
Answer:
hope this helps
Step-by-step explanation:
If you break the fraction into a whole number it would be 5 and 10 minus 5 is 5. so x=5