Write two subtraction equations to show how to find 15 - 7

Solution:

We need to find 15-7 using two subtraction equation.

First we split 15 and 7 as addition form.

Split 15 = 10 + 5

Because sum of 10 and 5 is 15

Split 7 = 5 + 2

Because sum of 5 and 2 is 7

Now we substitute into original expression.

(10 + 5) - (5 + 2)

Now we open the parentheses

10 + 5 - 5 - 2

We can see two positive number and two negative number.

Now we move one positive and one negative number together

10 - 5 + 5 - 2

Now we close in parentheses.

(10 - 5) + (5 - 2)

Two subtraction equation:

10-5  and  5-2

to find the total number of combinations, multiply the quantity of each item by each other:

2 pairs of shoes x 3 pairs of shorts = 6 different combinations.