(1)25+15=40,2×40=80,1600÷80=20,
列成综合算式是:1600÷[2×(25+15)];
(2)825-45=780,780÷60=13,15×3=45,
列成综合算式是:(825-15×3)÷60;
(3)30-10=20,3×20=60,1200+60=1260,
列成综合算式是:1200+3×(30-10);
(4)46-16=30,30×24=720,8+38=46,
列成综合算式是:(8+38-16)×24.
故答案为:1600÷[2×(25+15)],(825-15×3)÷60,1200+3×(30-10),(8+38-16)×24.