#### Answer

$\frac{150 trees}{1 acre}=\frac{1500 trees}{10 acres}$

#### Work Step by Step

We are given that 150 trees is to 1 acre as 1500 trees is to 10 acres. In order to write this as a proportion, we can write both relations as fractions.
150 trees is to 1 acre can be written as $\frac{150 trees}{1 acre}$
1500 trees is to 10 acres can be written as $\frac{1500 trees}{10 acres}$
Next, we can set both fractions equal to each other, which gives us a proportional relationship.
$\frac{150 trees}{1 acre}=\frac{1500 trees}{10 acres}$
Since the units in the numerators and denominators are different, we do not simplify any further.