C = 1 /2Rt solve for R

The train station clock runs too fast and gains 5 minutes every 10 days. how many minutes and seconds will it have gained at the end of 9 days?

What are the solutions of the equation? 5z^2 + 9z - 2 = 0 a. 1, -2 b. 1, 2 c. 1/5, -2 d. 1/5, 2

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.