Answer:
b
Step-by-step explanation:
Solve for b
<span>b² =81-36=45 </span>
<span>x²/a² - y²/b² =1 </span>
<span>plug in and choose</span>
Answer: 
Step-by-step explanation:
For a line to be parallel to another, it must have an equivalent slope. The equation,
, is in slope-intercept form. Thus, the slope of both lines must be -1/7. Then, using the slope-intercept formula, plug in 7 for x and 21 for y to get:



Thus, the slope of the line is:
.
Hope it helps :D