Answer:
9
Step-by-step explanation:
4x-7
4(4)-7
16-7
9
25
Square root of 25 is 5
Answer:
about 90
Step-by-step explanation:
15.4 rounds down to 15
5.7 rounds up to 6
15 × 6 = 90
Answer:
Step-by-step explanation:
Question 18:
arc SRQ = 360° - 98° - 115° = 147°
y = 147°/2 = 73.5°
arc SPQ = 98° + 115° = 213°
x = 213°/2 = 106.5°
Sorry, I don't know how to answer 19.
Answers:
Equation is 
Center is (-1, -2)
Radius = 5
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Work Shown:

center = (h,k) = (-1,-2)
radius = 5
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Explanation:
I grouped up the x and y terms separately. Then I added 1 to both sides to complete the square for the x terms. I cut the 2 from 2x in half, then squared it to get 1. In the next step, I cut the 4 from 4y in half to get 2, which squares to 4. So that's why I added 4 to both sides to complete the square for the y terms.
Each piece is factored using the perfect squares factoring rule which is a^2+2ab+b^2 = (a+b)^2
The last equation is in the form (x-h)^2 + (y-k)^2 = r^2
We can think of x+1 as x - (-1) to show that h = -1
Similarly, y+2 = y-(-2) = y-k to show that k = -2
The center is (h,k) = (-1,-2)
The radius is r = 5 because r^2 = 5^2 = 25 is on the right hand side in the last equation above.