626 Worked-Out Solutions to Exercises: Chapters 11 to 19
Multiplying through by 4, we get
2 x+ 8 =− 4
Subtracting 8 from each side gives us
2 x=− 12
Dividing through by 2 produces
x=− 6
- If we call the unknown number x, then we have the following equation to solve:
(x−x/10)/2 = 135
Multiplying through by 2 gives us
x−x/10= 270
Note that x−x/10 is the same as x− (1/10)x, or (9/10)x. So we have
(9/10)x= 270
Multiplying through by 10/9 gives us
(10/9)(9/10)x= 10/9 × 270
which simplifies to
x= 300
- Let’s call Bonnie’s weight, in kilograms (kg), the unknown x. Then Bruce’s weight in
kilograms is x+ 5, and Bill’s weight in kilograms is (x+ 5) + 10, or x+ 15. The total
weight is 200 kg. We can now write the equation
x+ (x+ 5) + (x+ 15) = 200
Applying the commutative law and adding the constants on the left side gives us
x+x+x+ 20 = 200
which simplifies to
3 x+ 20 = 200