How do i find what does z equals in 4z-11>1

In the figure below, triangle rpq is similar to triangle rts. what is the distance between p and q? a. 24 b. 42 c.50 d. 54

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.

Can anyone me with this question?