20 dogs are at the shelter.
The first thing we must do for this case is find the number of total guitarists.
We have then:

We now look for the relationship between the number of guitarists playing jazz alone to the total number of guitarists.
We have then:

Where,
x: number of guitarists playing jazz alone
From here, we clear the value of x.

Then, the number of guitarists who play classical solo is:

Answer:
30 guitarists play classical solos in the contest
First account: $6500
Second account: $8500
Set x is amount of money in first account
=> x + 2000 is money in second account.
X*3% + (x+2000)*4% = 535
=> x = (53500 - 8000) / 7
X = 45500 / 7 = 6500
=> account #1 = x = 6500
Acc #2 = x + 2000 = 6500 + 2000 = 8500
Answer
6 Gallons
Each gallon of water needs 6 teaspoons because 30/5=6
Now we know that teaspoons/6=amount of gallons
36/6=6 gallons
It's basically 5,000*2=10,000
and 10,000/2=5,000. your answer would be either they multiplied 5,000 by 2 and 10,000 divided by 2, they increased the sales by 5,000