3 Short question please in MIPS study help

A processor with a clock cycle time of 0.5 nanoseconds has a CPI of 4 for a particular program. What is the MIPS rating for this program?

A program is run on a system with two types of machine language instructions: type A instruction each require 3 clock cycles, while type B instructions each require 1 clock cycle. If 100 million type A instructions and 400 million type B instructions are executed, what is the CPI for this program?

For a particular program as run on a particular system, the CPU execution time is 1 second, the CPI is 4, and 750 million instructions were executed. What is the clock rate as measured in GHz?