ASAP PLS HELP IM GIVING 15 POINTS DONT PUT RANDOM STUFF JUST FOR THE POINTS

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.

What is the lcm of 16 and 40 ? 24 and 40 ?

Acollection of coins has value of 64 cents. there are two more nickels than dimes and three times as many pennies as dimes in this collection. how many of each kind of coin are in the collection?