Really confused by this, all help appreciated

Which is equivalent to 10/12? options: 10/18 5/6 3/12 9/11

Giuseppi's pizza had orders for $931.00 of pizzas. the prices were $21 for a large pizza, 514 for a medium pizza, and $7 for a small pizza. the number of large pizzas was two less than four times the number of medium pizzas. thenumber of small pizzas was three more than three times the number of medium pizzas. how many of each size of pizza were ordered?

Determine which expressions represent real numbers and which expressions represent complex number. asaaap! plis!