Equivalent expression for 5a+30

There is a spinner with 14 equal areas, numbered 1 through 14. if the spinner is spun one time, what is the probability that the result is a multiple of 2 or a multiple of 5?

Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. x^2 - 20 = x a. 5, 4 b. -5, -4 c. -5, 4 d. 5, -4

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.