First simplify the square roots:

Then simplify the last two terms:

Since 61 is prime, you can't take a rational root out of it.
I take it each student is going to make a block.
She has 25 + 28 students all together which is 53 students total
Each one requires 512 magnetic blocks
Therefore she needs 53 * 512 = 27136 blocks.
Twice a number (2x) decreased by 7 (- 7).
2x - 7
Two times a specfic number (x) subtracted by 7.
Yes! For example, 10 and 20 have 1, 2, 5, & 10 in common ^.^
Answer:
The prime factors are: 2 x 3 x 3 x 5 x 7
or also written as { 2, 3, 3, 5, 7 }
Written in exponential form: 2 x 3 × 3 x 5 ×1 x 7×1