The answer to this problem is 4
5(6x+5)-2(4x-1) = 30x+25-8x+2 = 22x+27
To find the lowest common denominator you need to know the factors of 5 and 11.
So make two lists:
5, 10, 15, 20, 25, 30, and so on.
11, 22, 33, 44, 55, 66, and so on.
Keep doing that until you find the lowest common number in the lists. The LCD will be 55.
To find the sales tax multiply the purchase price by the sales tax rate. Remember to convert the sales tax rate from a percent to a decimal number. Once the sales tax is calculated, it is added to the purchase price. The result is the total cost—this is what the customer pays.