Teachers and students of a certain grade organize a spring outing, and if they use multiple 45-seat buses alone, they are just full; Rent a 60-seat bus alone, you can rent one less, and there are still 30 seats left. Q:

(1) Find the number of people who participated in the spring outing this grade.

( 1+30/60)÷( 1/45- 1/60)

= 1.5÷ 1/ 180

=270 people

(2) It is known that the rental of 45-seat passenger cars is 250 yuan per car and that of 60-seat passenger cars is 300 yuan per car. These two kinds of buses were rented at the same time this spring outing, of which 60 were rented more than 45, and the rent used was less than renting one alone. How much will it cost according to this plan?

60-seat buses (270+45) ÷ (60+45) = 315 ÷105 = 3 vehicles.

45-seat bus 3- 1=2 vehicles

The rent is 250× 2+300× 3 = 500+900 =1400 yuan.