Help again and again.

Which speed is the fastest (use 1 mile ≈ 1.6 kilometers)? a. 12 miles/hour b. 18 feet/second c. 19 kilometers/hour d. cannot be determined

The lengths of all sides of a triangle are integers when measured in decimeters. one of the sides has length of 1 dm and another of 3 dm. find the perimeter of the triangle.'

Richard save $32 in march he saved $48 in april and $38 in may then richard spent $113 on a keyboard how much money does richard have left