20 12 in the seventh grade, someone taught me the first calculation problem on page 67 of mathematics ... I forgot my math book. As long as the title is ok, thank you. I love you.
Simplification: (1)12 (x-0.5); (2)-5( 1- 1/5x)(3)-5a+(3a-2)-(3a-7)(4) 1/3(9y-3)+2(y+ 1)
Exercise 2.2
Adoption. Oh, come on.