Need help with precalc homework!

Ive been working these for awhile and I need some help.

1.Find the area of a rectangle that is 6 times as long as it is wide. Express your answer in terms of w, the width of the rectangle in feet.

2.Find the value of the change in a purse that contains 3 times as many nickels as pennies, 5 more dimes than nickels, and 4 more quarters than dimes and nickels combined. Express your answer in terms of p, the number of pennies.

3.Mary has $5.90 in nickels, dimes, and quarters. If she has twice as many dimes as quarters and 8 more nickels than dimes, how many coins of each type does she have?

4.A 1.5-acre building is 5 times as long as it is wide. What are its dimensions? (Note: 1 acre = 43,560 ft2.)

2 answers for this one, smaller dimension and larger one

5.A jeweler has 7 rings, each weighing 22 g, made of an alloy of 10% silver and 90% gold. He decides to melt down the rings and add enough silver to reduce the gold content to 76%. What is the amount of silver to be added?

answer must be given in grams

6.If Ben invests $4200 at 3% interest per year, how much additional money must he invest at 4.5% annual interest to ensure that the interest he receives each year is 3.5% of the total amount invested?

thanks for any help