What are two solutions to x^2+4x+20=0

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

Solve this riddle: i am an odd number. i an less than 100. the some of my digit is 12. i am a multiple of 15. what number am i?

Plz hurry evaluate the expression a+b where a=8 and b=19