4x+2(x+ 13)= 146
4x+2x+26= 146
6x= 120
x=20
So x+ 13=20+ 13=33.
A: There are 33 chickens and 20 rabbits.
2. If there is a pencil X box, the pen has a 28-x box. According to the meaning of the problem, the equation is obtained:
12x+ 10(28-x)=300
12x- 10x+280=300
2x=20
x= 10
So 28-x=28- 10= 18.
A: There are 10 pencils and 18 boxes of pens.
3. If adults buy X tickets, then children buy 99-x tickets. According to the meaning of the question, the equation is obtained.
4x+2(99-x)=340
4x-2x+ 198=340
2x= 142
x=7 1
So 99-x=99-7 1=28.
A: I bought 7 1 adult tickets and sold 28 children tickets.