If 1 has x teachers, then 12X students, then a * * will cost 20* 12X+40*X, which is 240X+40X yuan.

Suppose there are x students and X/ 12 teachers, then a * * * is 20X+(X/ 12)*40, which is 20X+ 10X/3 yuan.

Let an angle be X, then its complementary angle is180-X. According to the meaning of the question: X = 3 (180-X)+10, X = 137.5 is calculated, so the size of the angle is/kloc-0.

13.AB passes through the parallel line GH of c and EF passes through the parallel line IK of d.

From AB//GH, angle DCH= angle BCD- angle BCH and angle BCH= angle ABC = 25.

DCH angle =20 degrees.

Similarly, angle CDI= = angle CDE-angle IDE, angle IDE= angle DEF, that is, angle E = 10.

Get the angle CDI = 20, so the angle DCH= angle CDI gets GH//IK.

Because AB//GH and EF//IK

So AB//EF