Final answer:
The red blood cell's size of 7 x 10^-8m, when expressed in standard notation, is 0.00000007 meters. This is done by moving the decimal point 8 places to the left, as indicated by the negative exponent in the scientific notation.
Step-by-step explanation:
The size of a red blood cell, which is 7 x 10-8m in scientific notation, can be expressed in standard notation as 0.00000007 meters. To convert from scientific to standard notation, you simply move the decimal point to the right for positive exponents and to the left for negative exponents, counting each move as one power of ten.
For instance, 7 x 10-8 means the decimal point in 7 is to be moved 8 places to the left, as the exponent is negative. Therefore, the standard notation will reflect this movement, giving us the direct answer in 2 lines: 0.00000007 meters (or 70 nanometers, since 1 meter = 109 nanometers).