Subtract 3 both sides first. R-3=ts²
next, divide both sides by t, (R-3)/t=s²
finally, take the square root of both sides
√(R-3)/t = s. 2nd choice.
Answer:
1/3?
Step-by-step explanation:

= 7.
Ratio means multiply/divide.
To get the next number, multiply number by common ratio.
To get a previous number, divide by common ratio.
Since we want the next number...
2nd term: 7 x -2 = -14
3rd term: -14 x -2 = 28
4th term: 28 x -2 = -56
5th term: -56 x -2 = 112
Keep going until 9th term!