what number I am if I am a factor of 90 but not a multiple of 6 and 9 i am greater than 10 but smaller than 20

How do you find the area of a triangle

If sec theta = 5/3 and the terminal point determined by theta is in quadrant 4, then

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.