Please I need help with this asap Explain

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.

Ten times the square of a non-zero number is eqaul to ninety times the number

Write the sine and cosine values of a, b, respectively, in the figure for (1) and (2) + explanation.