Answer:
Mia read 6 books
Explanation:
Let, L= number of books that Lucy read
and M= number of books that Mia read.
Given:
Lucy and Mia read 9 books in week.
L+M = 9
Mia read twice as many ad Lucy.
M = 2L or L=M/2
How many books did Mia read?
M?
Substitute L with M/2 in the equation L+M =9
M/2 +M =9 , find the common denominator
(M+2M)/2 =9, multiply both sides by 2, and add like terms in parenthesis
3M = 18, divide both sides by 3
M = 6 books