The sale discount is 10% and the question says senior citizens get a further discount of 8%. Thus, the total discount a senior citizen gets is 18%
100% - 18% = 82%
Senior citizens only pay for 82% of the value of the umbrella. Multiply 0.82, or 82%, with the value of the umbrella to get the final price.
Senior citizens pay $4.92 for the umbrella during the sale with their discount. Let me know if you need any clarifications, thanks!
~ Padoru