B KOH
I would say this is the base for the compound substance
The total amount that Staci had in hand is $200.00.
The ticket at that time costs $87.96.
One Tshirt costs, $30.00.
Now that she has paid ticket, she will deduct the ticket from the cash she has in hand, so as to know the amount she is remaining with.
Tha is, $200-$87.96 = $112.04.
∴ In hand Staci has $112.04 extra cash whereby she can purchase more t shirts.
To get the number of tshirt she can buy, she will divide the amount she has in hand by the amount per piece of t shirt.
For example, $112.04 / $30 = $3.73.
∴ Staci can only purchase threet shirts only at a total cost of $90 for all the t shirts which is $30 × 3 = $90.
Staci has excess of 22.04 after deducting ticket and the other amount she has used to purchase the extra t shirts.
That is, $112.04 - $90 = $22.04.
The molecular formula for compound is 
mass of compound is 0.670 g.
To calculate number of atoms first calculate number of moles in the compound as follows:
Molar mass of is 283.886 g/mol, thus,
Thus, number of mole of is 0.00236 mol.
From the molecular formula 1 mole of has 2 mol of P (phosphorus) and 5 mol of O (oxygen).
Thus, number of moles of P and O in 0.00236 mol of will be:
Similarly,
Now, in 1 mol of an element there are 
atoms.
Number of atoms of P will be:
Similarly, number of atoms of O will be:
Total number of atoms will be sum of number of atoms of P and O:
Therefore, total number of atoms in will be 
.
