Design a rectangular reinforced concrete beam to carry service loads of 1.25 kips/ft dead load (includes beam weight) and 2.60 kips/ft live load. The beam is a simple span and has a span length of 18 ft. The overall dimensions are limited to width of 10 in. and overall depth of 20 in. Use f′ c = 3000 psi and fy = 60,000 psi.