Hey just need some one to talk to

What signals you that factoring by grouping is the best method to use when factoring a problem?

Use set buikder notation to represent the following set: {, -2, -1, 0}

Astore sells two types of radios. one type sells $87 and the other for $119. if 25 were sold and the sales were $2495, how many of the $87 radios were sold a) 5 b) 20 c) 15 d)10