### Real analysis - Step Functions and Riemann Integrals

If f is defined on [a,b] and and are, respectively, a nondecreasing and a nonincreasing sequence of step functions such that for all k and all and for almost all , show that f is Riemann integrable on [a,b]. Notes from section of book below: Section 5 Notes: Theorem 5.1 If f is Riemann integrable on [a,b],