With theses math question! will mark brainliest 70 !

1. Let hardcover books = X

Paperback books would be 4x -3 ( 3 less than 4 times)

Now you have:

X + 4x-3 = 447

Simplify:

5x - 3 = 447

Add 3 to each side:

5x = 450

Divide both sides by 5:

x = 450/5

x = 90

He has 90 hardcover books.

2. 300 miles / 25 miles per gallon = 12 gallons of gas.

12 gallons x $$ per gallon = $48 dollars

3. Subtract base pay from total:

1916 - 800 = 1,116 worth of commissions.

Divide commissions by percentage:

1116 / 0.09 = $12,400 total sales.

4.

Find the median of the heights: 65-50 = 15. 15/2 = 7.5

Median = 50+7.5 = 57.5

The equation would be |h-57.5| < 7.5

32 ≤ cost ≤ 48 dollars.

Step-by-step explanation:

1. Let x be number of hardback books. Then:

x + 4x - 3 = 447

5x = 450

x = 90 hardbacks.

2. If she is 200 miles from her destination her car will use 200/25 = 8 gallons of gas, and cost her 8*4 = $32.

If the distance is 300 miles then the cost  will be  (300/25) * 4 =  $48.

3. He earned 1916 - 800 = $1116 commission on his sales.

4. ( I can't see any options).