B1. At the work action, it was necessary to transport 350 wheelbarrows of material. If each worker had transported three more wheelbarrows, 15 fewer workers would have been needed. How many workers were there and how many wheelbarrows did each transport? Write down the answer.
B1. Let $x$ be the number of workers and $y$ be the number of carts. From the problem statement, we can write the equations: $x \cdot y=350$ and $(y+3) \cdot(x-15)=350$. We solve the system of two equations with two unknowns: from the first equation, we can express $x=\frac{350}{y}$ and substitute it into the second equation. We get $\left(\frac{350}{y}-15\right) \cdot(y+3)=350$, which simplifies to $y^{2}+3 y-70=0$. Factoring the quadratic equation, we get $(y-7)(y+10)=0$, from which we read the solutions $y=7$ and $y=-10$, where the second solution is not meaningful. When we calculate $x=50$, we answer: 50 workers were involved, and each pushed 7 carts.

![](https://cdn.mathpix.com/cropped/2024_06_07_4401d59a37898c9fd2b4g-13.jpg?height=48&width=1628&top_left_y=2323&top_left_x=277)

![](https://cdn.mathpix.com/cropped/2024_06_07_4401d59a37898c9fd2b4g-13.jpg?height=69&width=1636&top_left_y=2370&top_left_x=276)

![](https://cdn.mathpix.com/cropped/2024_06_07_4401d59a37898c9fd2b4g-13.jpg?height=57&width=1639&top_left_y=2424&top_left_x=274)

Solutions $y=7, y=-10$ (the second is not meaningful) ..........................................................................

Answer: 50 workers were involved, and each pushed 7 carts.................... 1 point