A town council intended to spend $70000 on buying trees. Because of the size of the order the supplies reduced the price of each tree by $10 and the council now decided to spend only $60000. If the number of trees finally obtained is 100 more than the number originally intended, find the number of trees finally obtained.

Can you please set up an equation for me and explain it, because I really have no idea how to work it out. Thank you!

If the original order was for t trees at a price p,

p*t = 70000

but at a price of $10 less, they get 100 more trees for 60000

(p-10)(t+100) = 60000

substituting in from the first equation,

(70000/t - 10)(t+100) = 60000
t = 1400

so, they finally got 1500 trees