Question

An unknown number b is 10 more than an unknown number k. The number b is also k less than 8. The equations to find k and b are shown below:

b = k + 10
b = −k + 8

Which is a correct step to find k and b?

Write the points where the graphs of the equations intersect the x-axis.
Write the points where the graphs of the equations intersect the y-axis.
Add the equations to eliminate k.
Multiply the equations to eliminate b.

Answer 1

add the equations to eliminate k

b = k + 10
b = -k + 8
----------add
2b = 18
b = 9

now sub 9 in for b in either equation to find k
b = k + 10
9 = k + 10
9 - 10 = k
-1 = k

check..
b = -k + 8
9 = - (-1) + 8
9 = 1 + 8
9 = 9 (correct)