USING TOOLS In Exercises 23-26, use a graphing calculator to solve the system of linear equations.
23. 0.2 x+0.4 y=4
-0.6 x+0.6 y=-3
24. -1.6 x-3.2 y=-24
2.6 x+2.6 y=26
25. -7 x+6 y=0
0.5 x + y=2
26. 4 x-y=1.5
2 x + y=1.5

27. MODELING WITH MATHEMATICS You have 40 minutes to exercise at the gym, and you want to burn 300 calories total using both machines. How much time should you spend on each machine? (See Example 3.)