[Question]
9 2 5 = 90

[Answer]
9 * 2 * 5 = 90

[Question]
8 3 9 = -19

[Answer]
8 - 3 * 9 = -19

[Question]
2 1 8 = 10

[Answer]
2 + 1 * 8 = 10

[Question]
5 4 9 = 10

[Answer]
5 - 4 + 9 = 10

[Question]
3 10 3 = -10

[Answer]
3 - 10 - 3 = -10

[Question]
4 1 6 = -2

[Answer]
4 - 1 * 6 = -2

