How to find the maximum height projectile motion?

The gades foundation and hbm corporation are eager to donate generously to their favorite charities. the gades foundation donated $250 in the first month, and each month afterward their cumulative donation total increases by 100$ the hbm corporation donated $64, in the first month, and each month afterward their cumulative donation total increases by 75%. in which month will the hbm corporation's cumulative donation total first exceed the gades foundations' cumulative donation total?

What is the value of x? enter your answer in the box. photo attached.

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?