To subtract we can count backwards. Start at and count back .

To add we count up. Start at and count up .

To subtract we can count backwards. Start at and count back .

To solve this problem we can set up a proportion and cross multiply to solve for our unknown.

First we cross multiply.

Then we divide each side by to isolate the .

If we count all the squares together we have squares.

To add we count up. Start at and count up .

Multiplication can be thought of as repeated addition, or as objects in a group.

means adding one time.

and

Or we can think of this as grouping objects. We have group, with objects in each group. We can count up the total number of objects, in this case triangles.

When you add and together you get . does not equal because . does not equal because . does not equal because .

To solve this problem, we first need to find out how many of Justin's toys will fit on the shelves. If we have shelves, and toys fit on each shelf, we can multiply those two numbers together to find out the total number of toys that will fit. Let's let represent the number of toys that will fit.

Justin has toys, so to find out how many don't fit on the shelves we need to know what is left over, so we subtract. Let's let represent the number of toys left over.

To add we count up. Start at and count up .