Split it into 2 equations
2x-9 = 7
2x = 16
x = 8
And another equation
2x-9 = -7
2x = 2
x = 1
The answer is x =1, x= 8
1 step: 
,

, then

.
2 step: 
, then




and

will have form

.
3 step: Solve this system

and dividing first equation on second we obtain

. So,

and

,

- the common ratio.
4 step: Insert

into equation

and obtain

, from where

.
10
13.50 per set
+.45 per day value
she got 20 sets
5 days after would be
13.50 ×20=270
value of 20 sets at 13.50 a set on day one was 270.00
.45×20=9.00
the 20 sets gain 9 dollars a day
9×5=45
9 dollars a day times 5 days is 45 dollars
45+270=315
11
Answer:
h = 8
Let the unknown number be h for height
V = LWH
984 = 20.5 x 6 x h
984 = 20.5 x 6h
984 = 123h
984 ÷ 123h
= 8