Answer:

Step-by-step explanation:
Given that,
Mass of material, m = 6900 grams
Volume of the material, V = 4.5 quarts
We need to find the density in pounds per cubic foot
We know that,
1 pound = 453.59 grams
⇒ 6900 grams = 15.21 pounds
Also, 1 cubic foot = 29.92 quarts
4.5 quart = 0.15 feet³
Density = mass/volume
Or

Hence, the density of the material is 
3/5 = 6/10 (which is 60%) 100% - 60% = 40%
Answer:
90x+10y
Step-by-step explanation:
Add 89 and 1
Add 5 and 5
90x+10y in this order