(7 + x) + 7x=? I need help

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.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Drag the tiles to the correct boxes to complete the pairs. not all tiles will be used. identify the domain for each of the given functions.