How many valence electrons would an element with the following electron configuration have: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p3

Carson has only $20 bills and $10 bill in her wallet. the total value of the bills is $50. she has 1 more $20 bill than $10 bills. how many each kind of bill does carson have? a. one $20 and two $10 bills b. two $20 bills and one $10 bill c. one $20 bills and three $10 bills d. two $20 bills and two $10 bills

Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

Isaac wants the equation below to have no solution when the missing number is placed in the box. which number should he place in the box?