1, the store bought a batch of sandals at the price of 13 yuan, and the price was 14, 8 yuan. When there were five pairs left, 88 yuan earned money besides buying all the sandals. How many pairs of sandals are there?

A: When five pairs are sold, they have already made a profit in 88 yuan, so they can make a profit of 88+ 14.8×5= 162 yuan, and each pair earns14.8-13 =1.8 yuan, so * * has 65430. Comprehensive formula: (88-14.8× 5) ÷ (14.8-13) = 90 pairs.

If a commodity is sold at a fixed price, both parties can make a profit. In 50 yuan, if 10 is sold at 80% of the fixed price, then its profit is equivalent to 12 being sold at a reduced price in 30 yuan. What's the price of this commodity per unit?

Answer: 80% price sells 10, which is equivalent to the original price selling 10×80%=8 pieces. According to the pricing, if 12 pieces are sold at a reduced price in 30 yuan, it is 30× 12=360 yuan, which is equivalent to the original pricing of 12-8=4 pieces, so the original pricing is 360÷4=90 yuan. Comprehensive formula: 30×12 ÷ (12-10× 80%) = 90 yuan.

3. A bookstore sells a kind of calendar, and every time it sells 1 book, it can earn a profit of 18 yuan. After selling a part, the price of each copy will be reduced by 10 yuan, and all of them will be sold out. It is known that the number of calendars sold at reduced prices is 2/3 of the original sales calendars. Bookstores sell this kind of calendars, making a profit of 2870 yuan, and bookstores sell them.

A: The number of calendars sold at a reduced price is 2/3 of the original price, which means that the ratio of the original price to the reduced price is 3: 2, so we can consider selling every three books at the original price together with two books at a reduced price, so that every five books can make a profit18× 3+(18-10 )× 2 = 70 yuan. Comprehensive formula: 2870 ÷ [18× 3+(18-10 )× 2 ]× (3+2) = 205 copies.