For this case, the first thing we will do is identify variables:
x: number of washings.
y: amount of ounces of remaining shampoo.
We write the equation taking into account:
1) bottle of shampoo contains 60 ounces
2) He used ounce of shampoo each time he washes his hair
The equation is:
y = -x + 60
Then, for y = 24 we have:
y = -x + 60
24 = -x + 60
We clear x:
x = 60-24
x = 36
Answer:
the number of washes after which 24 ounces will remain in the bottle is:
36 washes.
So to rewrite it so that we can find the side, we just need to isolate the a variable.
So firstly, divide by 6 on both sides of the equation: 
Next, square root each side, and your answer should be 
1. 0.6
2. 10
3. -½
the answers are thrre ...
