Look at this please i dont need help im just trying to tell everybody something

John used linear combination to solve the system of equations shown. he did so by multiplying the first equation by -3 and the second equation by another number to eliminate the x-terms. what number did jonas multiply the second equation by? 4x-6y=23x+5y=11

The given diagram shows the parts of a right triangle with an altitude to the hypotenuse. using the two given  measures, find the other four.

Is the number 128.439 a rational number