Answer:
150 oz.
Step-by-step explanation:
There are already 150 ounces of alloy of nickel.
Of this 150 oz, 70% is pure i.e. nickel content = 150(0.7) = 105 oz
Now available is
Nickel Other metals
105 45
Let x oz of pure nickel is added.
Then new alloy will have 105+x oz nickel in total of 150+x oz.
Percentage pure = 
Simplify to get

Hence answer is 150 oz should be added.
4 miles= (10-s) x 1hr. S could stand for the speed of the wind, since it is taking away from the typical speed of the bike.
So the original price is "x".
the discounted price by 10% is P(x) = 0.9x.
the price minus a $150 coupon is C(x) = x - 150.
so, if you go to the store, the item is discounted by 10%, so you're really only getting out of your pocket 90% of that, or 0.9x, but!!! wait a minute!! you have a $150 coupon, and you can use that for the purchase, so you're really only getting out of your pocket 0.9x - 150, namely the discounted by 10% and then the saving from the coupon.
C( P(x) ) = P(x) - 150
C( P(x) ) = 0.9x - 150