Simplify this please

Every time you drive you will experience a combination of driving conditions and environments.

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of

Consider the sequence below. 3 , 1 , 1/3 , 1/9 , select the explicit function which defines the sequence.