Answer:
Read the explanation!
Step-by-step explanation:
<em>Let the "certain number" be </em>
<em>. </em>
(
is a symbol for multiplication).
<em>Create a few equations and expressions:</em>
The sum of 12 and a certain number: 
The product of 3 and the number: 
The sum of 12 and a certain number is equal to the product of 3 and the number:
= 
Solve!
12=3x-x
12=2x
x=6
Answer:
15
Step-by-step explanation:
f(x) = 5x + 40
…………………………
when x = -5
f(-5) = 5(-5) + 40
= -25 + 40
= 40 - 25
= 15
Answer:C) x2 + y2 =45
Step-by-step explanation:
The equation of a circle in standard form is (x-h)2+(y-k)2=r2.
Since you know the center is (0,0), you can sub this is value in for h and k, then use the point (3,6) to sub in for x and y and you will find r2 =45. Hope that helps :)
