10. (12 points) 19 gardeners went to plant trees, 4 of them went to plant trees on Street $A$, and the remaining 15 went to plant trees on Street $B$. In the evening, when they returned to the dormitory, Gardener A said, “Although we are fewer in number, we took the same amount of time as you.” Gardener B said, “Although we are more in number, the length of our street is 4 times the length of your street.” If the intervals between the trees they planted are the same and each person planted the same number of trees, and trees are only planted on one side of the street and at both ends of the street, then these 19 gardeners planted a total of $\qquad$ trees.
【Solution】Solution: Let each person plant $x$ trees, then the number of trees planted on $B$ Street is $15 x-1$, and the number of trees planted on $A$ Street is $4 x-1$.
$$
\begin{array}{l} 
15 x-1=4 \times(4 x-1) \\
15 x-1=16 x-4 \\
16 x-15 x=4-1 \\
x=3 \\
3 \times 19=57 \text { (trees) }
\end{array}
$$

Answer: These 19 gardeners planted a total of 57 trees.
Therefore, the answer is: 57.