1. The problem asks for the percent change in Joy's weight. She weighed 80 kg before and now weighs 76 kg. 2. Calculate the change in weight: $$\text{Change} = 76 - 80 = -4$$ kg. The negative sign shows a decrease. 3. Calculate the percent change using the formula: $$\text{Percent change} = \left( \frac{\text{Change}}{\text{Original value}} \right) \times 100 = \left( \frac{-4}{80} \right) \times 100 = -5\%$$. So, Joy's weight decreased by 5%. 4. The next problem asks for the percent change in the amount raised by the Mathematics Club. Last year they raised 1800, this year 450 more than last year. 5. Calculate this year's amount: $$1800 + 450 = 2250$$. 6. Calculate the change: $$2250 - 1800 = 450$$. 7. Find the percent change: $$\left( \frac{450}{1800} \right) \times 100 = 25\%$$ increase. 8. So, the Mathematics Club raised 25% more this year than last year.