Fertilizer runoff has a negative impact on aquatic ecosystems because
a. it causes plants and algae to grow quickly, suffocating organisms in the water
b. phosphorus is not found in nature
c. phosphorus is poisonous to living organisms
d. living organisms do not require phosphorus in order to survive

The answer is a. it causes plants and algae to grow quickly, suffocating organisms in the water. The rapid growth of organisms due to fertilizer runoff leads to a process called eutrophication. When the vegetation dies, the process of decomposition leads to the formation of excessive amounts of carbon dioxide, which in turn suffocates aquatic animals.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer