Problem 25 a freelance writer earns $20 for each blog post and $60 for each feature article. how many feature articles did the writer produce last week? last week, the number of blog posts was 10 more than twice the number of articles sold. last week the writer earned a total of $700 from blog posts and featured articles.

The given are:
cost for each blog = $20
cost for each feature article = $60
blog = 10+2(number of articles sold)
total earnings = $700

where, 
a = article
b = blog

to solve,
60(a)+20(10+2a)=700
60a+200+40a=700
200+100a=700
100a=700-200
100a=500
a=500/100
a=5
The total feature articles produced last week was 5.

to check, 
a+b=700
60(5)+20[10+2(5)]=700
300+20(10+10)=700
300+200+200=700
700=700

Indeed, the number of articles produced last week was 5.