Answer:
25% of 200 is 50
Step-by-step explanation
40% of a number is 80
.40 * n = 80
Divide each side by .4
.40 n/.4 = 80/.4
n = 200
The number is 200
Now lets find 25 percent of that number
.25 * 200 = 50
Let us bear in mind the equivalent value of these coins:
One dime = $0.10
One quarter = $0.25
Let x = number of dimes
y<span> = number of quarters</span>
Since the boy has 70 coins in total, we can say that:
<span>x + y = </span><span>70 </span>(can be written as x = 70 – y)
Since the boy has a total of $12.40, we can say that:
0.10x + 0.25y = 12.40
To solve this problem, we need to solve this system of equation. We have to substitute the value of x as written in the first equation (x = 70 –y)
0.10(70 – y) + 0.25y = 12.40
7 – 0.10y + 0.25y = 12.40
0.15y = 5.40
y = 36
X = 70 – 36
X = 34
Therefore,<span> the boys </span>has<span> 34 dimes and 36 quarters. To check our answer, we just have to check if his money would total $12.40.</span>
34 dimes = $3.40
36 dimes = $9.00
<span>Total </span><span>$12.40</span>
(-1 + 6)^2 <span>+ (4+5)^2 = </span>106
Answer:
(1) 2π - x² = 0 (2) x = 2.5 cm (3) perimeter = 10 cm
Step-by-step explanation:
(1)The area of the circular coin without the inner square removed is πr² where r = 3 cm is the radius of the coin. So, the area of the coin without the inner square removed is πr² = π(3 cm)² = 9π cm²
The area of the square of x sides removed from its center is x².
The area A of the each face of the coin is thus A = 9π - x²
Since the area of each face of the coin A = 7π cm²,
then
7π = 9π - x²
9π - 7π - x² = 0
2π - x² = 0
(2) Solve the equation 2π - x² = 0
2π - x² = 0
x² = 2π
x = ±√(2π)
x = ± 2.51 cm
Since x cannot be negative, we take the positive answer.
So, x = 2.51 cm
≅ 2.5 cm
(3) Find the perimeter of the square
The perimeter of the square, p is given by p = 4x
p = 4 × 2.51 cm
= 10.04 cm
≅ 10 cm
I mean, I don't know how to explain a generic way to solve this. Ask me about the specific train of thought if you are interested:
7 * 18 + 45 / 3 - 2 = 139
