A school canteen bought 200 whole loaves of bread and 100 brown loaves of bread. A discount of 10% was offered on each whole loaf, whereas a discount of 13.5% was allowed on each brown loaf of bread. Calculate the percentage discount on the cost of all the loaves of bread bought.

Kuna aina mbili za mikate iliyonunuliwa:

• Idadi ya mikate myeupe = 200
• Punguzo la mikate myeupe = 10%
• Idadi ya mikate ya kahawia = 100
• Punguzo la mikate ya kahawia = 13%

Kwa kuwa bei maalum ya mkate haijatolewa, tunafikiria kuwa bei ya awali ya mkate mmoja (iwe mweupe au kahawia) ni $P$.

Gharama ya awali ya mikate myeupe = $200 \times P = 200P$
Gharama ya awali ya mikate ya kahawia = $100 \times P = 100P$
Jumla ya gharama ya awali ya mikate yote = $200P + 100P = 300P$

Kiasi cha punguzo kwa mikate myeupe = $10\%$ ya $200P = 0.10 \times 200P = 20P$
Kiasi cha punguzo kwa mikate ya kahawia = $13\%$ ya $100P = 0.13 \times 100P = 13P$
Jumla ya kiasi cha punguzo = $20P + 13P = 33P$

Asilimia ya punguzo la jumla huhesabiwa kwa kugawanya jumla ya kiasi cha punguzo kwa jumla ya gharama ya awali, kisha kuzidisha kwa 100%.

Asilimia ya punguzo la jumla kwenye gharama ya mikate yote iliyonunuliwa ni: