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.