4) Jessica sold half of her comic books and then bought 8 more. She now has 13. How
many did she begin with?

a) Let her  comic books be x

b) as she sold half it will be

  + 8 = 13  ( as she sold half and then she bought 8 more that means plus and then now she have 13 that means = 13)

c ) to solve to find the books she have we need to

+ 8 = 13

Transpose

 = 13 - 8

= 5

x = 5 × 2

x = 10

the comic books were 10

we can even cross- check to see if the value is right instead of x put 10

+ 8 = 13

5 +8 = 13

13 = 13

Cross-checked