Answer:
this is hard too
Step-by-step explanation:
Answer:
D.
Step-by-step explanation:
Set this up as a ratio with #parts of tank on top and #minutes on the bottom and then solve it as a proportion with x being the unknown number of minutes in the second ratio.

Notice the 1 in the numerator of the second ratio. This is because a whole tank is represented by 9/9 which is the same thing as 1.
Cross multiply to solve for x:

To solve for x we will multiply both sides by 9/5:

9/5 and 5/9 cancel each other out when multiplied leaving simply "x" on the left. And multiplying on the right:

which divides to 3.6 minutes
Answer:
-4
Step-by-step explanation:
-129 = 6(7 + 7x) - 3
Distribute the 6 into the parentheses.
-129 = 42 + 42x - 3
Add like terms.
-129 = 39 +42x
Subtract 39 from both sides.
-168 = 42x
Divide 42 from both sides.
-4 = x