Explanation

To find the average (arithmetic mean) of a and b, we need to first solve for a and b.

Given equation: 10a + 10b = 35

Divide both sides by 10: a + b = 3.5

Since we want to find the average of a and b, we can use the fact that the average of two numbers is equal to their sum divided by 2.

So, (a + b)/2 = 3.5/2

= 1.75

Therefore, the average (arithmetic mean) of a and b is 1.75.