A: It's said that a 20 yuan membership card can enjoy a 20% discount B: Yes, last time I bought a book, plus the cost of the card, I still have 12 yuan left! What was the original price of the book?

A: It's said that a 20 yuan membership card can enjoy a 20% discount B: Yes, last time I bought a book, plus the cost of the card, I still have 12 yuan left! What was the original price of the book?

The book price is X Yuan before the discount
X-0.8X-20=12
0.2X=32
X=160
The original price of the book is 160 yuan

Six mathematical questions
The meaning of fractional division and integer division () are both known () and () for () operation
A number divided by a fraction is the reciprocal of ()
One in two is () times one in three
Four out of seven of () is three out of five
5 / 8 of a project is completed in 5 days, with an average of ()
5 / 8 of a number is 1 / 12. This number is ()

The meaning of fractional division is the same as that of integer division, both of which are known (divisor) and among them (divisor) and (quotient) operation. A number divided by a fraction is equal to the reciprocal of this number multiplied by (the fraction). 1 / 2 of 2 is (3 / 2) times of 1 / 3. (4 / 7 of 21 / 20) is 3 / 5 kg

（-0.04）x（-20）x(-5)
(- 2) x (- 6.5) / (1 / 3)
6 + (- 1 / 5) - 2 - (+ 11.7)
-68x4-（3.5)÷（-0.010
(- 2 to the third power) X5 - (- 6 to the third power) △ 8
24x (3 / 4-1 / 6-3 / 8) / (- 5)

（-0.04）x（-20）x(-5)
=（-0.04）×[(-20)×(-5)]
=（-0.04）×100
=-4
(- 2) x (- 6.5) / (1 / 3)
=13 △ 1 / 3
=13×3
=39
6 + (- 1 / 5) - 2 - (+ 11.7)
=6+（-0.2）-2-11.7
=5.8-2-11.7
=3.8-11.7
=-7.9
-68x4-（3.5)÷（-0.01）
=-272-（-350）
=-272+350
=78
(- 2 to the third power) X5 - (- 6 to the third power) △ 8
=（-8）×5-（-216）÷8
=-40-（-27）
=-40+27
=-13
24x (3 / 4-1 / 6-3 / 8) / (- 5)
=(3 / 24 × 4-1 / 24 × 6-3 / 24 × 8) / (- 5)
=（18-4-9）÷（-5）
=5÷（-5）
=-1