The inner angles of a triangle are proportional to the numbers 3-5 and 7. What is the largest of its angles?

Let the value of the angle CAB = 3 * X0, then, by condition, the value of the angle ACB = 5 * X0, and the angle ABC = 7 * X0.

The sum of the inner angles of the triangle is 180, then (3 * X + 5 * X + 7 * X) = 180.

15 * X = 180.

X = 180/15 = 12.

Then the angle CAB = 3 * 12 = 36, angle ACB = 5 * 12 = 60, angle ABC = 7 * 12 = 84.

Answer: The largest angle of the triangle is 84.