Question 21.
Frank packs and weighs his school backpack. The backpack weighs
3 pounds. Then Frank puts in a textbook that weighs 25 pounds and
removes a notebook that weighs 8 ounces. Which expression can be used
to find the weight of the backpack now in ounces? (1 pound = 16 ounces)
A 48 + 32-8 C 60 + 32 - 8
B 48 + 40 - 8
D60 + 40 - 8

complete the square on the right side of the equation;

-5(x + 0)^2 + 15

answer: d. y = -x^2 + 15

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

allowed for the prediction of the properties of missing elements.

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs