There are two layers of books on the bookshelf. There are more than 50 books on the first layer and 1 / 3 on the second layer. How many books are there on the bookshelf?

There are two layers of books on the bookshelf. There are more than 50 books on the first layer and 1 / 3 on the second layer. How many books are there on the bookshelf?

50 books account for 3 / 5 + 1 / 3-1 = 1 / 15 50 / (3 / 5 + 1 / 3-1) = 750 books

A bookshelf has two layers, 40% of which are books on the upper layer. If 48 books are taken from the upper layer and put into the lower layer, 75% of which are books on the lower layer, how many books are there on the bookshelf?
What's the formula

Upper level now = 1-75% = 25%
Total = 48 (40% - 25%) = 320 copies

Simple calculation of 1 / 28 × 4 + 74 × 25% - 0.25 × 2

28 × 1 / 4 + 74 × 25% - 0.25 × 2
=28 × 1 / 4 + 74 × 1 / 4-1 / 4 × 2
=1/4x(28+74-2)
=1/4x100
=25
If you don't understand this question, you can ask,
In addition, please send and click my avatar to ask me for help,

What energy does the steam turbine convert into what energy?

Briefly speaking, the principle of nuclear power generation: nuclear power plant is composed of nuclear island and conventional island. The nuclear fuel made of uranium is fissioned in the equipment of "reactor" (i.e. nuclear island) and generates a lot of heat energy. The heat energy is brought out by steam generator, pressurizer, main pump and other equipment (referred to as primary circuit), mainly through

A practical problem about the fractional equation 150x = 150 − X2X + 2 is worked out in connection with practice. It requires complete expression, sufficient conditions and no solution

A factory needs to produce a batch of 150 parts. First, Party A will do it alone for one day, and the rest will be done by Party B. the time taken by Party B is two days less than the time taken by Party A to finish 150 parts alone. It is known that the work efficiency of Party B is twice that of Party A. how many parts does Party A do every day?

What are the two kinds of losses of hydro generators? In the process of producing electric energy from natural hydro energy, there are various losses, such as hydro energy loss, energy conversion loss, and so on?

The loss of energy conversion of hydraulic turbine: channel head loss, runner clearance leakage loss, runner conversion energy loss, bearing mechanical loss, tail water outlet kinetic energy loss, etc?

There are 300000 cars in a city at the end of 2010. It is estimated that 6% of the last year's cars will be scrapped every year, and the annual number of new cars is X. in order to protect the environment, the total number of cars should not exceed 600000, so how many new cars should be added every year?

This is a question about the summation limit of sequence. It is known from the question: 2111: 30 * 6% + X 2012: (30 * 6% + x) * 6% + x = 30 * (6%) ^ 2 + X * 6% + X 2013: ((30 * 6% + x) * 6% + x) * 6% + x = 30 * (6%) ^ 3 + X * (6%) ^ 2 + X * 6% + X ...

How many jin are 100 calories

Calories are calories, Jin is weight, both can not be converted, and intake of food calories to produce how much fat varies from person to person, some people even eat less will grow fat

Given that the absolute values of a ^ 2-6a + 9 and B-1 are opposite to each other, the value of formula [A / (a-b)] - [B / a] is?

∵（a－3）²≥0,|b－1|≥0
And: (A-3) & sup2; + | B-1 | = 0
∴a－3＝0,a＝3
b－1＝0,b＝1
a/（a－b） －b/a＝3/2－1/3＝7/6

Is the voltage at both ends of a superconductor connected circuit zero?
the sooner the better!

This topic depends on the specific situation. If the power supply is an ideal power supply, that is to say, no matter what circuit elements or loads in the circuit, it can output a stable voltage. Then the voltage at both ends should be the power supply voltage, while the current in superconductor is infinite. But this kind of power supply can not exist
In the actual circuit, any power source has its power and maximum output current. If a superconductor is connected, it is the theoretical maximum output current. The voltage is the maximum power / output current. Usually, the power source is burnt out