Question

If a = b /c-b , find the value of b when a = 3 and c = 10 *

3 points

a) 7

b) 7 whole 1/2

c) 8

3) If S=4πr^2 , find the value of S when r = 10 whole1/2. *

3 points

C) 1638

b) 1836

a) 1386

If a/b - d = 2c /b ,find the value of c when a =3 , b = 4 and d = -5. *

3 points

a) 1/2

b) 11

c)11 whole 1/2

choose the correct answers​

Answer 1

Answer:

15

Step-by-step explanation:

a+b=8 becomes a=8-b

b+c=10 becomes b=10-c

c+a=12 becomes c=12-a

Now subtract two of the equations that contain the same variable. I’ll pick two that contain an a: c+a =12 & a+b=8. Subtracting the latter from the former eliminates the “a”s, leaving c-b=4. Adding b to both sides to isolate c gives c=b+4. From above we can take b=10-c to substitute for b in c=b+4, giving us c=(10-c) + 4). Simplify the right side to c=14-c, add c to both sides, giving 2c=14, & then divide both sides by 2 to obtain c=7.

Replace the c in b=10-c with 7 to have b=10–7, so that b=3.

You can choose which a to solve for. I’ll select a+b=8, substituting 3 for b to have a+3=8, subtract 3 from both sides, gives us a=5.

Finally add 5+3+7 together to find that a+b+c=15.