4. In order to recover funds, a store in 480 yuan sells both A and B commodities. It is known that the added goods earned 20%, and the goods B lost 20%. What is the profit and loss result of the store?

The cost price of the two commodities is

480/( 1+20%)+480/( 1-20%)

=400+600

= 1000 yuan

1000-480*2=40 yuan

Lose 40 yuan

At the same time, two trains depart from Party A and Party B relatively. The speed of the express train is150km, and the speed of the local train is 90km. They meet at a distance of 240 kilometers from the midpoint. How many kilometers is it between Party A and Party B?

Solution: the express train runs more than the local train 150-90=60 km/h.

Then the express train is 240×2=480 kilometers longer than the local train.

Meeting time =480/60=8 hours

Distance between Party A and Party B = (150+90) × 8 =1920km.

There is a circular swimming pool in the park. Grandpa runs around the swimming pool 20 times a day. If the radius of the swimming pool is 38 meters, how many meters does Grandpa Li Run swim every morning?

Solution: Run 2× 3.14× 38× 20 = 4772.8m every day.

7. The newly developed roller has solved a difficult problem of expressway in China. Front wheel radius 1.5m, 8 revolutions per minute. How many meters does the roller advance per minute?

Solution: Forward 2× 3.14×1.5× 8 = 75.36 m.

There are 360 red balloons and yellow balloons in the shop, of which 25% are red balloons and 24 are yellow balloons. The remaining red balloons and yellow balloons are just equal. How many red balloons and yellow balloons are there?

Solution: 24 yellow balloons were sold, leaving 360-24=336.

At this time, the yellow balloon is regarded as the unit of 1, so Red Balloon has 1/( 1-25%)=4/3.

Originally there were 24+336/(1+4/3) = 24+144 =168 balloons.

Originally there were 360- 168= 192 Le Ballon Rouge.