Can anyone help me in this question I need help

Complete the steps to find 4.830 ÷ 5

Tom drove 206 miles in 3.9 hours. estimate his average speed.

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