7x9=(7x10)-(7x▲)
The way we solve this problem is by setting the equation equal to ▲
We want to isolate ▲ by itself on one side of the equation.
We can do this by first simplifying the numbers multiplied together.
7 x 9 = 63 and 7 x 10 = 70
63 = 70 - 7x▲
Next, we want to subtract 70 from both sides.
-7 = - 7x▲
Finally, to get ▲ completely by itself, we can divide both sides by -7
1 = ▲ which is our final answer :)
