Every positive number has two square roots - a positive and a negative (unless the value is 0).
The length of something can only be a positive number and since there is only one positive square root, there is only one answer.
Divide 45 by 60 which gives you 0.75. To check your answer, multiply 0.75 by 60 then add that answer to -45. So, the answer is 0.75
9.125 E10 is the same as 9.125 × 10¹⁰ in standard form.