Could 8.8 cm, 8.0 cm, and 8.8 cm be the side lengths of a triangle?

An arc subtends a central angle measuring 7pi/4 radians what fraction of the circumference is this arc?

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)

What is the sum of these mixed numbers 4 2/3+ 3 1/9