<u>Let's solve this problem step-by-step</u>:
- <em>x: it is the delta in the equation given in your picture</em>
<em />
<u>We know (7*10) - (7*x) is equivalent to the 7*(10-x)</u>
⇒ based on the Distributive Properties
<em />
<em> </em><u>So:</u>
<em> </em>
<u>Thus delta (the little triangle in this problem) in this case is 1</u>
<u></u>
<u>Answer: 1</u>
<u></u>
Hope that helps!