1. Joe studied the sketch. “Just a circular lawn,” he said, “made up of a ring of turfing and a circular flower bed. For a lawn five times the diameter of the flower bed, I’ll quote £40 for the turfing.” “What if we reduced the overall diameter of the lawn by a foot, but increased the flower bed’s diameter by one foot?” asked Charlie. Joe smiled. “Same rate and strictly by area. It would be £35 instead.” What was the original planned diameter of the lawn?

Lawn diameter 20 feet

Lawn diameter 18 feet

Lawn diameter 24 feet