Twice the difference of a number and nine is 20. someone write it as an number equation. pls and thx

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

In order to be invited to tutoring or extension activities a students performance 20 point higher or lower than average for the

Jim had 3,067.48 in his checking account he wrote a check to pay for two airplane tickets. his account now has 1,845.24.