First, what you want to do is subtract the price you sell it for by how much you got it for.
In this case, your equation would look like this: 114 - 90 = 24
You added $24 to the price that you bought. The amount added to the price would be $24
Then you would divide the amount added to the price by the amount it costed you to buy. It would end up as a decimal:
24 ÷ 90 = 0.266 (infinite 6's)
Then with the decimal you got, you would multiply it by 100 to get the markup rate percentage.
0.266 × 100 = 26.66
The markup rate would be 26.66% (26.7 if you round).
