You need 20 pounds of grass seed to plant grass inside the baseball diamond below. About how many pounds of grass seed

Revenue = price * quantity of backpacks
quantity of backpacks = -2p + 50

For p = 9: -2(9) + 50 = -18 + 50 = 32
thus, revenue = 9 * 32 = 288

For p = 12: -2(12) + 50 = -24 + 50 = 26
therefore, revenue = 12 * 26 = 312

For p = 12.50: -2(12.50) + 50 = -25 + 50 = 25
thus, revenue = 12.50 * 25 = 312.50   MAXIMIZES REVENUE

For p = 15: -2(15) + 50 = -30 + 50 = 20
so, revenue = 15 * 20 = 300

Plans A and D are incorrect because plan C states that it would have a consistent price for 8 weeks, whereas plan D would require 16 weeks to reach $12, which eliminates A and D as options. If the price were to be increased by 10% weekly, it would take 5 weeks to hit $12, as 10% of $8 amounts to 80 cents, leading to a total increase of $4 after 5 weeks, making the price $12. This confirms that B is the right choice.

Honestly, I find Mrs. Garcia's method easier to perform mentally. It hinges on how familiar you are with your multiples of 5. (5*15 = 75 is a multiplication I often use)

Melissa's approach involves calculating 5*20 = 100 and 5*9 = 45, then combines the 3-digit result 100 with the 2-digit result 45, yielding 145. Adding 45 to 00 is simple and doesn’t require carrying digits, thus the arithmetic is fairly straightforward.

Mrs. Garcia's technique involves computing 5*14 = 70 and 5*15 = 75, then summing these two-digit results. Many people may not readily recall that 5*15=75, which complicates forming that product. The addition of 70 and 75 requires a carrying operation, making the math somewhat more complex. The resulting total is 145.

(The rationale behind my preference for Mrs. Garcia's method is that I can achieve the final sum by simply doubling 7 tens, followed by adding 5. The only 3-digit number to remember mentally is the ultimate total.)

_____Subtraction introduces a slight complication, yet reshaping it as $5(30 -1) = $150 - 5 = $145 is possible.
Or, you may reframe it as $5(28 +1) = $140 +5 = $145.
Dividing an even number by 2 to find the product of 5 is straightforward when you append a zero.
  5*14 = 10*7 = 70
  5*28 = 10*14 = 140.