Samuel orders a salad for $2.50 and spaghetti for $8.25. The sales tax is 7.5%. What is the total cost of the billing including tax
The total cost of the salad is $2.50 and the total cost of the spaghetti is $8.25. The total cost of both items before tax is $2.50 + $8.25 = $<<2.5+8.25=10.75>>10.75.
To calculate the sales tax, multiply the total cost by the tax rate: $10.75 * 7.5% = $<<10.75*7.5*.01=0.80625>>0.80625.
The total cost of the billing including tax is $10.75 + $0.80625 = $<<10.75+0.80625=11.55625>>11.55625. Answer: \boxed{11.56}.