A girl had 20 coins in nickels and dimes whose sum was $1.40. She spent 65cents , using 8 coins. She now has ? nickels.
2 answers:
Answer:
9 Nickles
Step-by-step explanation:
Let n = number of nickles and d = number of dimes
d + n = 20 -----------(1) [ total number of coins 20 ]
Dimes = $0.10
Nickles = $0.05
0.1d + 0.05n = $1.40 ---------- (2) [20 coins worth $1.40]
Since d + n = 20
∴ n = 20 - d
Let's substitute n in equation (2)
0.1d + 0.05(20-d) = 1.40
0.1d + 1 - 0.05d = 1.40
0.1d + 0.05d = 1.40 - 1
0.05d = 0.4
d =
d = 8
Now put value of d in equation (1)
n + 8 = 20
n = 20 - 8
n = 12
Let's check 8(0.1) + 12(0.05) = $1.40
Now she spent 65 cents using 8 coins.
The only combination of 8 coins worth $0.65 is
5d + 3n = $0.65
Hence, she used 5 dimes and 3 nickles.
Now she has 12 - 3 = 9 Nickles
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Answer: a) Length of wire to replace old one=9ft
b) Length of wire=3.09ft
Leftover wire=0.91ft
Step-by-step explanation: from the right angle triangle, Tan&=20/15
&=53.13°
Length of wire,x=cos 31.13=x/15
15cos31.13
X=9
b) Tan&=10/6
Tan^-110/6
&=59.05
Length= 6cos59.04
X=3.09
4-3.09=.91= leftover wire
To find the cofactor of
We cross out the Row and columns of the respective entries and find the determinant of the remaining matrix with the alternating signs.
Therefore in increasing order, we have;