The width of a virus is 2.0 x 10 to the(-7)th meter. Write this number in standard decimal notation

If a fair 6 sided cube is rolled 60 times, theoretically how many times should you expect to roll a 4 or a 5?

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

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)