Question

Monica paid sales tax of $2.80 when she bought a new bike helmet. If the sales tax rate was 7%, how much did the store charge for the bike helmet before tax?

Answer 1

7 % of cost price is 2.80 , What about 1%?

7 = 2.80

1 = x   (where x is the price value of 1% in dollars)

We simplify the above equation, so:

7 × x = 2.8 × 1  →  7x = 2.8 →  x = 2.8 / 7  →   x = 0.4 dollars

We know that 100%  represents the whole price,

so if 1% is 0.4 dollars, then 100% will be 0.4 × 100 = 40 dollars

Therefore the store charged $40  dollars for the helmet before tax