Answer:68-c=M
35
Step-by-step explanation:m is the number needed, it is the thing we are trying to find, so lets start out by putting it as the thing we need to equal
=m
Now, what equals m?
However many blocks Tegan still needs to make. What do we know? We know she needs 68 in all, and she has already made some. If we take away c, which is how many she has made, then we will have the number she still needs.
68-c
=m
68-c=m
