In Exercises, make the given changes in the indicated examples of this section and then so...

In Exercises, make the given changes in the indicated examples of this section and then solve the resulting problems.

In Example, in the first line, change 34 to 37.

EXAMPLE Office complex energy-efficient lighting

In designing an office complex, an architect planned to use 34 energy-efficient ceiling lights using a total of 1000 W. Two different types of lights, one using 25 W and the other using 40 W, were to be used. How many of each were planned?

Since we want to find the number of each type of light, we

Also, since there are 34 lights in all,

We also know that the total wattage of all lights is 1000 W. This means

Therefore, there are 24 25-W lights and 10 40-W lights. The total wattage of these lights is 24(25) + 10(40) = 600 + 400 = 1000. We see that this checks with the statement of the problem.