In making a lawn in the garden, the cost of fencing is $20 per metre and the cost of flower -planting is $50 per metre square. Let x be the length of a side of the lawn in metres.
(a) If $ F is the cost of constructing the fence, find a formula connecting F and r.
(b) If $ Pis the cost of flower-planting, find a formula connecting P and x.
(C)
If $ T is the total cost of making the lawn, find a formula connecting T and x.​