1, choose the right question x, choose the wrong question or not choose15-x.

4X- 1*( 15-X)=45

X= 12

Correct selection of 12 questions

4X- 1*( 15-X)=35

X= 10

Select the correct 10 question.

Assume that each person can take X kilograms of luggage.

Because only C needs to be paid to 8 yuan, and three people need to be paid to 4 yuan, which is a dual relationship.

150-X=2( 150-3X)

X=30

Everyone can take 30 kilograms of luggage.