Step-by-step explanation:
step 1. a circle with r = 2 has area of (pi)r^2 = (pi)(4) = 4pi
step 2. a circle with r = 3 has area of (pi)r^2 = (pi)(9) = 9pi
step 3. the area, A, of a circle is half the sum of the area of the circles with r = 2 and r = 3
step 4. A = (4pi + 9pi)/2 = 13pi/2 = 6.5(pi).
step 5. the answer is not 6.5 but is 6.5(pi) or 6.5 times pi.
<u>Answer:</u>
- The cost of 1 dozen doughnut is $6 and the cost of a dozen croissant is $10.
<u>Step-by-step explanation:</u>
<u>We know that:</u>
- D = Cost of a dozen doughnut
- C = Cost of a dozen croissant
- 10D + 7C = 130
- 6D + 4C = 76
<u>Work:</u>
6D + 4C = 76
7(6D + 4C = 76)
42D + 28C = 532
- 40D - 42D = 520 - 532
- => -2D = -12
- => 2D = 12
- => D = 6
<u>Now, let's substitute the value of D into the first equation.</u>
- 10D + 7C = 130
- => 10(6) + 7C = 130
- => 60 + 7C = 130
- => 7C = 70
- => C = 10
Hence,<u> the cost of 1 dozen doughnut is $6 and the cost of a dozen croissant is $10.</u>
Hoped this helped.
