To maintain the correct ratio of birds to mammals to reptiles, let  be the number of birds,  be the number of mammals, and  be the number of reptiles.

We can then write the following equation:

Solve for .

Since the question asks for the number of reptiles, we will need to find the value of .

The zoo has  reptiles.

If  workers can paint  square feet of wall in  hours, that means each painter must paint  square feet of wall in  hours. Thus, each painter must paint  square feet of wall in each hour.

Now, if each painter can paint  square feet in one hour, then  painters can paint  square feet of wall in one hour. As the six painters can paint  square feet in one hour, then it will only take them  hours to paint  square feet.

Start by finding the commission that Sarah earned.

Convert the percentage into a decimal:

Next, multiply this by the amount of products that Sarah was able to sell to find her commission.

Make sure that you rounded to the nearest cent.

Now, add the commission to the base pay to find her total paycheck.

In order to find what the value of the goods she sold was, we need to first figure out the amount she earned from her commission. Do this by subtracting out the weekly base pay from her total pay.

Now, we know that  must be the amount from the commission. Since Emily earns  of her total sales as commission, this amount must also represent  of the value of the goods she sold.

We can then set up the following equation. Let  be the value of goods Emily sold.

The part, the whole, and the percent of a percentage problem can be related by the proportion statement

Set  equal to the whole, and 19 and 95 equal to the part and the percent, respectively:

Set the cross-products equal:

Divide both sides by 95 to solve for :

,

the correct response.

If we let and be a part and a whole of a percent problem, then the that is of is

.

In this problem, 9 is the part and 3 is the whole. Thus,

,

the correct response.

, so 9% 0f 3 is equal to

,

the correct response.

Recall how to find the percent change for two values:

The new value in this case would be the value from February, and the old value would be the value from January.

Plug in the correct values to find the percent change:

Based on the information provided, you know that a "standard" batch could be represented as:

This lets you set up a proportion:

The variable  represents the number of cups of prunes in the full batch. Begin solving by cross-multiplying:

Then, just divide by :

The entire recipe contains 6 cups of prune slices.

To imagine your sequence, think of a few values:

And so forth...

In the second element, you add one value of seventeen. In the third, you add two. This means that in the th, you will add a total of  seventeens; therefore, you could write your value as: