343 is the answer because 14 tens is 1 hundred and 4 tens
The diagonals of a rhombus are perpendicular bisectors of each other, and are also angle bisectors. The 4 congruent right triangles the rhombus is cut into by the two diagonals are 30-60-90 degree triangles, the longer leg is √3/2 of the hypotenuse, √3/2 of 10=5√3. so the longer diagonal is twice of 5√3=10√3
