You can set up an system of equations
x=2y+8
x-y=25
Substitute x in to the second equation
2y+8-y=25
y+8=25
y=17
Substitute the y back in to the first equation.
x=2(17)+8=42
Answer:
d= bv + r
Treat it like you would a normal equation. Multiply by b and add r to isolate d.

= 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!