ANSWER
A) B = 575 - 32m; T = 350 + 13m
B) 479 birds and 389 trees.
C) 5 months
Step-by-step explanation
Let the number of months be m.
Let the number of birds be B
Let the number of trees be T.
A) Initially there are 575 birds, but the number of birds decreases by 32 each month. This means that after m months, the number of birds is:
B = 575 - 32m
Initially there are 350 trees, but the number of trees increases by 13 each month. This means that after m months, the number of trees is:
T = 350 + 13m
B) After 3 months, m = 3.
This means that:
B = 575 - 32(3)
B = 575 - 96
B = 479 birds
This also means that:
T = 350 + 13(3)
T = 350 + 39
T = 389 trees
After 3 months there are 479 birds and 389 trees.
C) We want to find the number of months it will take the number of birds and trees to be equal. We have to equate B and T and find m:
575 - 32m = 350 + 13m
Collect like terms:
32m + 13m = 575 - 350
45m = 225
Divide both sides by 45:
m = 225 / 45
m = 5 months
It will take 5 months.