What type of number is -5.41? Choose all answers that apply

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

15m is what percent of 60m; 3m; 30m; 1.5 km? the last one is km not m

I’m really confused and need your assist me with this question i’ve never been taught