Xiao Ming's family of three went to travel, and the original price of the two travel agencies was the same. The following preferential ways are introduced respectively: a. Travel agency: full price fo

Xiao Ming's family of three went to travel, and the original price of the two travel agencies was the same. The following preferential ways are introduced respectively: a. Travel agency: full price for adults and 50% discount for children. ★ Youjia Hotel Products Factory

There are x people in the whole family, and the expenses of A travel agency are 1 yuan, and those of B travel agency are y2 yuan.

Get: y 1=90+? 0? 5×90×(x- 1)=45+45x

y2=2/3×90x=60x

Let y 1=y2.

D: 45+45x=60x

Solution: x=3

If y 1 > y2

Then 45+45 times > 60 times

x3

A: when X < 3, choose travel agency b; When x=3, you can choose travel agencies A and B; When X > 3, travel agency A will be selected.