In the forest, the number of spruces is 40% of oak trees. How many percent are oaks of spruce?

The number of spruces in the forest from oak is – 40%, which means that the rest of the oaks are – 60%;

We will solve by the method of drawing up the proportion;

The equality of two relations is called proportion;

We find the% of oak trees from spruce, which we denote by “x”;

We will take 40% of spruces as 100%, since it is from them that we will count the% of oaks;

40 – 100%;

60 – x%;

The product of the extreme terms of the proportion is equal to the product of its middle terms;

To find the unknown extreme term of the proportion, you need to divide the product of the middle terms of the proportion by the known extreme term;

x = (60 × 100) / 40;

x = 150;

Answer: 150% are oaks from firs.