Answer: C. 1.05(3.99p + 2.50b)
Explanation:
Hi, to answer this question we have to write an inequality with the information given: 
Paint can cost : 3.99 
Brush cost : 2.50 
Sale tax rate : 5% : 0.05 (decimal form, 5/100= 0.05) 
So, to calculate the total cost, first, we have to multiply each cost by the quantity of each item. 
3.99 p + 2.50 b 
Where p is the number of paint cans and b is the number of brushes 
Since we have to add the tax rate we have to multiply that expression by (1 +0.05) , the percent increase. 
. 1.05(3.99p + 2.50b) (option C) 
 
Feel free to ask for more if needed or if you did not understand something.