Net Electrostatic Force on a Point Charge

Three point charges are arranged in a right triangle: $q_1 = 2.0\ \mu\text{C}$ is at the origin, $q_2 = -4.0\ \mu\text{C}$ is at $(3.0\ \text{m}, 0)$, and $q_3 = 5.0\ \mu\text{C}$ is at $(0, 4.0\ \text{m})$. What is the magnitude of the net electrostatic force on $q_1$ in newtons? $(k = 9.0 \times 10^9\ \text{N} \cdot \text{m}^2/\text{C}^2)$