Question

Lwazi has R30,00 and buys three hamburgers at R7,50 each

Answer 1

Lwazi spends 3 * R7,50 = R<<3*7.5=22.50>>22.50 on hamburgers.
Lwazi now has R30.00 - R22.50 = R<<30-22.5=7.50>>7.50 left. Answer: \boxed{7.50}.