For problems like this you can move the y's on the bottem up top by fliping the sign of the exponent (in this case 7 to -7) and MULTIPLYING it with EVERYTHING on top, then because of properties of multplication you can add the exponents to combine them into one term (in this case add 3 and -7 to get -4)

If any of this does not make sense let me know and ill try to clarify better
Multiple each number I think
Answer: Phone C
Using quick mental math, we can do 8% of 10 to get 0.8, which is close to the value of 0.0845*10. Also fairly quick is moving the decimal point over 1 spot to the right and we go from 0.0845 to 0.845 and that rounds to 0.8 when rounding to one decimal place. Recall that 8.45% = (8.45/100) = 0.0845
If you want to compute out the four results with a calculator, then it would look like this:
0.0845*20 = 1.69
0.0845*25 = 2.1125
0.0845*10 = 0.845
0.0845*18 = 1.521
and this shows that no other result (but choice C) is close to 0.8
So that's why the answer is choice C
For this case we have the following data:


So that the figure can be a rectangle, its diagonals must be equal, that is, 
In this way we have:

Clearing x we have:


Thus, x must be equal to 10 so that the figure is a rectangle.
Answer:

Option A
Answer: red 36 m
Step-by-step explanation: base plus base = 18 / 2 = 9 * 4 = 36 m