Question

A student bought a calculator and a textbook for a course in algebra. He told his friend that the total cost was $160 (without tax) and that the

calculator cost $10 more than twice the cost of the textbook. What was the cost of each item? Let x = the cost of a calculator and y= the cost of the textbook
X+ y = 16
X=2y+10
. Solve the system by using the method of substitution.

Answer 1

Answer: x = 14, y = 2. or (14,2)

Explanation:

1. make an unknown number stand by itself. in this case, I will subtract x from both sides in the first equation.

y = 16 - x

2. now that I know the formula for y, I will plug it in to the second equation.

x = 2 (16 - x) + 10

3. I solve the second equation.

x = 32 - 2x + 10

x = 42 - 2x

3x = 42

x = 14

4. I substitute the answer x into the first equation.

x + y = 16

14 + y = 16

y = 2

Answer 2

50

Explanation:

With the 2 linear equations provided X+ y = 16 X=2y+10

Solving for x

x=2y+10
(2y+10)+y=160
3y+10=160

3y=160−10

3y=150

y = 150/3
y = 50

now replacing y with 50:
x=2y+10
x=2(50)+10

x=100+10

x=110